The Recordset object is the primary object used to manipulate data in Access databases (and other databases as well, via ODBC connections). Although there is a Recordsets collection (the collection of all open Recordset objects in a database), it is not much use, except to list the open recordsets and their SQL statements, as in the following code sample:
Private Sub cmdListRecordsets_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim intCount As Integer Dim strTable As String strTable = "Orders" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) intCount = dbs.Recordsets.Count Debug.Print intCount & _ " recordsets in current database (before opening a recordset)" Set rst = dbs.OpenRecordset(strTable, dbOpenTable) intCount = dbs.Recordsets.Count Debug.Print intCount & _ " recordsets in current database (after opening a recordset)" For Each rst In dbs.Recordsets Debug.Print "Open recordset: " & rst.Name Next rst End Sub
A new Recordset object is automatically added to the Recordsets collection when you open the recordset, and it is automatically removed when you close it. Note that when you first count the recordsets in the preceding code, the count is 0; after setting a recordset variable, it is 1. The position of the Recordsets collection in the DAO object model is shown in Figure 8-1.
Figure 8-1. The Recordsets collection in the DAO object model
|
You can create as many recordset variables as you want, and different recordsets can access the same tables, queries, or fields without causing a problem. You can even open two recordsets from the same data source, and this is not a problem, so long as you refer to the recordsets by the variables used to assign them, not by their names.
TIP:
See the Name property section later in this chapter for a discussion of why it is unwise to use the Name property to reference a recordset.
There are five types of recordsets: Table-type, Dynaset, Snapshot, Forward-only, and Dynamic. (See the Type property section for a discussion of recordset types.) Each Recordset object contains a collection of Fields that represents the fields in the underlying table(s). You can list the field names and values, but you will just get the values in the current record, unless you first go to a particular record. For example, the following code moves to the last record in a recordset and lists the field names and values for that record:
Private Sub cmdListFields_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim fld As Field strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst .MoveLast For Each fld In .Fields Debug.Print fld.Name & " value: " & fld.Value Next fld .Close End With End Sub
Although you can reference a Recordset object in the Recordsets collection by any of the following syntax variants, it is advisable to use its variable instead to avoid possible ambiguity.
Recordsets(0)Recordsets("name")Recordsets![name]
The Recordsets collection has two properties and one method, which are shown in Table 8-1.
Table 8-1: Members of the Recordsets Collection Type | Name | Description |
|---|
Property | Count | Indicates the number of Recordset objects in the Recordsets collection |
Property | Item | Retrieves a Recordset object either by its index in the collection or by its name |
Method | Refresh | A nonfunctional method |
The Recordset object has 32 properties (shown in Table 8-2) and 24 methods (listed in Table 8-3). It also has two collections: the Fields collection, a collection of the individual fields in the recordset; and the Properties collection, a collection of the individual properties supported by the Recordset object.
Table 8-2: Recordset Object Properties Property | Description |
|---|
AbsolutePosition | The relative position of the current record |
BatchCollisionCount | Number of records that did not complete the last batch update |
BatchCollisions | Array of bookmarks representing rows that had a collision during the last batch update |
BatchSize | For batch updates, the number of statements to send back to the server in each batch |
BOF | Flag indicating whether the record pointer is at the beginning of the file |
Bookmark | Value that uniquely identifies a particular record in the recordset |
Bookmarkable | Indicates whether a recordset supports bookmarks |
CacheSize | Determines the number of records from an ODBC data source that will be cached locally |
CacheStart | The bookmark of the first record to be cached locally |
Connection | The Connection object that owns the recordset |
DateCreated | Date and time the recordset was created |
EditMode | Indicates the recordset's editing state |
EOF | Flag indicating whether the record pointer is at the end of the file |
Filter | Expression that filters records from the recordset |
Index | Name of the current index |
LastModified | Bookmark indicating the most recently modified record |
LastUpdated | Date and time the recordset was last updated |
LockEdits | The type of locking in effect when editing |
Name | The name of the Recordset object |
NoMatch | Flag indicating whether a search was successful |
PercentPosition | Relative position of the current record in the recordset |
RecordCount | Number of records in the recordset |
RecordStatus | The update status of the current record in the next batch update |
Restartable | Indicates whether a recordset supports the Requery method |
Sort | Expression defining the sort order of records |
StillExecuting | Indicates whether an asynchronous operation has finished executing |
Transactions | Indicates whether the recordset supports transactions |
Type | The recordset (or cursor) type |
Updatable | Indicates whether the recordset can be updated |
UpdateOptions | Indicates how the SQL WHERE clause is constructed for each record during a batch update and whether the update should use an UPDATE statement or a DELETE followed by an INSERT |
ValidationRule | Defines a validation rule used to validate data as it is changed |
ValidationText | Text displayed when a record fails to meet the validation criteria |
Table 8-3: Recordset Object Methods Method | Description |
|---|
AddNew | Adds a new record to an updatable recordset |
Cancel | Cancels execution of a pending asynchronous method call |
CancelUpdate | Cancels any pending updates |
Clone | Creates a duplicate Recordset object |
Close | Closes the recordset |
CopyQueryDef | Returns a copy of the QueryDef object originally used to create the recordset |
Delete | Deletes the current record |
Edit | Prepares a record for editing |
FillCache | Fills all or part of a recordset's local cache |
FindFirst | Finds the first record that meets designated criteria |
FindLast | Finds the last record that meets designated criteria |
FindNext | Finds the next record that meets designated criteria |
FindPrevious | Finds the previous record that meets designated criteria |
GetRows | Retrieves rows into a two-dimensional array |
Move | Moves the record pointer either forward or backward |
MoveFirst | Moves to the first record of the recordset |
MoveLast | Moves to the last record of the recordset |
MoveNext | Moves to the next record of the recordset |
MovePrevious | Moves to the previous record of the recordset |
NextRecordset | Retrieves the next set of records returned by a multipart SELECT query |
OpenRecordset | Creates a new recordset |
Requery | Reissues the query that created the recordset |
Seek | Locates a record that meets the criteria based on the current index |
Update | Saves changes to a record |
Access to the Recordset Object
- Creatable
- No
- Returned by
The OpenRecordset method of the Connection object
The Recordsets property of the Connection object
The OpenRecordset method of the Database object
The Recordsets property of the Database object
The Clone method of the Recordset object
The OpenRecordset method of the Recordset object
The OpenRecordset method of the TableDef object
Recordsets Collection Properties
| Count |  |
|
Data Type
Integer
Description
Indicates the number of recordsets in the Recordsets collection. See the code sample in the introduction to this chapter for an example of its usage. As far as I can see, there is little (if any) practical use for this property.
| Item |  |
|
| Recordsets.Item(Index) |
Argument | Data Type | Description |
|---|
Index | Integer | The ordinal position of the Recordset object in the Recordsets collection, or a string containing the name of the Recordset object to be retrieved from the collection |
Data Type
Recordset object
Description
Retrieves a particular Recordset object from the Recordsets collection. A Recordset object can be retrieved either based on its ordinal position in the collection or based on its name. (But see the Name section later in this chapter for the reasons why it is unwise to reference a recordset based on its name.) Mostly, recordsets are manipulated by means of the variable used to set them, since this is the best way to assure that you are working with the correct recordset.
Recordsets Collection Methods
Refresh
Recordsets.Refresh Although the documentation lists Refresh as a method of the Recordsets object in Help and the Object Browser, actually this method is inapplicable to the Recordset object, since Refresh applies only to persistent objects. (Since recordsets exist only in memory, the Recordsets collection is not a collection of persistent objects.) Calling the method, however, does not generate an error; it simply has no effect.
Recordset Object Properties
Table 8-4 summarizes which properties apply to each type of Recordset object and whether the property setting is read/write (RW) or read-only (RO) for Jet ( J) and ODBCDirect (O) databases, or for both Jet and ODBCDirect workspaces ( JO). A blank cell indicates that the property does not apply to either type of workspace. In cases where the property is always read-only with a value of False, that is indicated by an F in the cell.
Table 8-4: Recordset Property Summary Property | Table | Dynaset | Snapshot | Forward-Only | Dynamic |
|---|
AbsolutePosition | | RW | RW | | RW |
| | JO | JO | | O |
BatchCollisionCount | | RO | RO | RO | RO |
| | O | O | O | O |
BatchCollisions | | RO | RO | RO | RO |
| | O | O | O | O |
BatchSize | | RW | RW | RW | RW |
| | O | O | O | O |
BOF | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
Bookmark | RW | RW | RW | | RW |
| J | JO | JO | | O |
Bookmarkable | RO | RO | RO | | RO |
| J | JO | JO | | O |
CacheSize | | RW/RO | RO | | RO |
| | J/O | O | | O |
CacheStart | | RW | | | |
| | J | | | |
Connection | | RW | RW | RW | RW |
| | O | O | O | O |
DateCreated | RO | | | | |
| J | | | | |
EditMode | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
EOF | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
Filter | | RW | RW | RW | |
| | J | J | J | |
Index | RW | | | | |
| J | | | | |
LastModified | RO | RO | RO | | RO |
| J | JO | O | | O |
LastUpdated | RO | | | | |
| J | | | | |
LockEdits | RW | RW/RO | RW/RO | RW | RO |
| J | J/O | J/O | J | O |
Name | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
NoMatch | RO | RO | RO | | |
| J | J | J | | |
PercentPosition | RW | RW | RW | | RW |
| J | JO | JO | | O |
RecordCount | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
RecordStatus | | RO | RO | RO | RO |
| | O | O | O | O |
Restartable | F | RO | RO | RO | RO |
| J | JO | JO | JO | O |
Sort | | RW | RW | | |
| | J | J | | |
StillExecuting | | RO | RO | RO | RO |
| | O | O | O | O |
Transactions | RO | RO | RO (F) | RO (F) | |
| J | J | J | J | |
Type | RO | RO | RO | RO | RO |
| J | JO | JO | JO | O |
Updatable | RO | RO | F/RO | F/RO | RO |
| J | JO | J/Oa | J/Oa | O |
UpdateOptions | | RW | RW | RW | RW |
| | O | O | O | O |
ValidationRule | RO | RO | RO | RO | |
| J | J | J | J | |
ValidationText | RO | RO | RO | RO | |
| J | J | J | J | |
AbsolutePosition
Data Type
Long
Description
This misleadingly named property sets or returns the relative record number of a recordset's current record. It is a zero-based number corresponding to the ordinal position of the current record in the recordset, ranging from zero to one less than the record count. If there is no current record (for example, for an empty recordset), AbsolutePosition returns -1.
TIP:
Despite the "Absolute" in the property name, this property is not stable and certainly is not a record number. It changes every time records are added to or deleted from a recordset. Use the Bookmark property to set a variable you can use to return to a particular record after moving the record pointer by a search or requerying.
VBA Code
This code displays the ordinal number of the record in a recordset while iterating through it:
Private Sub cmdAbsolutePosition_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenSnapshot) With rst .MoveFirst Do While Not .EOF Debug.Print !LastName & " record--No. " & .AbsolutePosition + 1 .MoveNext Loop .Close End With dbs.Close End Sub
| BatchCollisionCount |  |
|
Data Type
Long
Description
For ODBCDirect workspaces only, this property returns the number of records that did not complete in the last batch update. It corresponds to the number of Bookmarks in the BatchCollisions property.
| BatchCollisions |  |
|
Data Type
Variant Array
Description
For ODBCDirect workspaces only, this property returns a variant containing an array of bookmarks, representing rows that had a collision during the last batch Update call. The number of elements in the array can be determined by retrieving the value of the BatchCollisionCount property.
BatchSize
Data Type
Long
Description
For ODBCDirect workspaces only, this property sets or returns the number of statements sent back to the server in each batch. The default value is 15. Setting BatchSize to 1 causes each statement to be sent separately; you might do this when working with those database servers that don't support batch updates.
BOF
Data Type
Boolean
Description
The BOF property (the name is derived from "Beginning of File") indicates that the current record position is before the first record in a recordset. It is useful for determining whether you have gone beyond the beginning of the records in a recordset when moving backward. In a recordset with no objects, this property is True. However, if you delete the last remaining record in a recordset, BOF may remain False until you attempt to reposition the record pointer. See Table 8-5 for a summary of what happens when you use the Move methods with different combinations of the BOF and EOF properties.
Table 8-5: The Move Methods with BOF and EOF BOF/EOF | MoveFirst, MoveLast | MovePrevious, Move <> | Move 0 | MoveNext, Move > 0 |
|---|
BOF=True, EOF=False | Allowed | Error | Error | Allowed |
BOF=False, EOF=True | Allowed | Allowed | Error | Error |
Both True | Error | Error | Error | Error |
Both False | Allowed | Allowed | Allowed | Allowed |
Table 8-6 shows what happens to the BOF and EOF properties after using Move methods that don't find a record.
Table 8-6: When Move Methods Don't Find a Record | BOF | EOF |
|---|
MoveFirst, MoveLast | True | True |
Move 0 | No change | No change |
MovePrevious, Move <> | True | No change |
MoveNext, Move > 0 | No change | True |
VBA Code
This code uses the BOF marker to prevent going beyond the first record when iterating backward through a recordset:
Private Sub cmdBOF_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim fld As Field strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst .MoveLast Do While Not .BOF Debug.Print !CategoryName .MovePrevious Loop .Close End With End Sub
Bookmark
Data Type
Variant array of Byte data
Description
Uniquely identifies the current record in a recordset. By retrieving the value of a record's Bookmark property, you can later return the record pointer to that record. It is the closest thing Access has to a record number. You can use bookmarks on recordsets whose Bookmarkable property is True, which is always the case for recordsets based entirely on Jet tables. For recordsets based on other databases, Bookmarkable may not be True, in which case you can't use bookmarks.
VBA Code
See the code sample in the Requery section for an example of using the Bookmark property to return to the same record after requerying; the following code sample shows another way the Bookmark property can be useful in returning to the previous record after a failed search:
Private Sub cmdBookmark_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim varBookmark As Variant strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst If .Bookmarkable = False Then MsgBox "This recordset is not bookmarkable -- exiting!" Exit Sub Else MsgBox "This recordset is bookmarkable -- continuing!" End If varBookmark = .Bookmark .Index = "PrimaryKey" .Seek "=", 5 If .NoMatch Then .Bookmark = varBookmark Debug.Print !CategoryName .Close End With End Sub
| Bookmarkable |  |
|
Data Type
Boolean
Description
The Bookmarkable property indicates whether you can use bookmarks in a recordset. If you are not sure that the tables underlying a recordset are all Jet tables, you can check this property before attempting to use bookmarks. See the Bookmark section for an example of its usage.
CacheSize
Data Type
Long
Description
Sets or returns the number of records retrieved from an ODBC data source that will be cached locally. The value must be between 5 and 1200, but it can't be greater than available memory permits. Setting CacheSize to 0 turns off caching. Using a cache can improve performance, since retrieving data from a local cache is faster than retrieving it from the server.
CacheStart
Data Type
String
Description
The CacheStart property (used in conjunction with CacheSize and FillCache) sets or returns a value that specifies the bookmark of the first record in a dynaset-type recordset containing the data to be locally cached from an ODBC data source in a Jet workspace.
Connection
Data Type
Connection Object
Description
Sets or returns the Connection object that owns the recordset, for ODBCDirect workspaces only.
| DateCreated |  |
|
Data Type
Date/Time
Description
Returns the date and time the recordset was created. Note that this is usually different than the date the underlying table was created.
VBA Code
Private Sub cmdDateCreated_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) Debug.Print rst.Name & " recordset created on " & rst.DateCreated End Sub
| EditMode |  |
|
Data Type
Long
Description
Indicates the state of editing, as listed in Table 8-7.
Table 8-7: The EditMode Property Settings Named Constant | Value | Description |
|---|
dbEditNone
| 0 | No editing operation is in progress. |
dbEditInProgress
| 1 | The Edit method has been invoked, and the current record is in the copy buffer. |
dbEditAdd
| 2 | The AddNew method has been invoked, and the current record in the copy buffer is a new record that hasn't been saved in the database. |
The value of the EditMode property can be useful in determining whether you should use the Update or CancelUpdate method when editing is interrupted. The following code sample shows the EditMode value for various stages of editing records.
VBA Code
Private Sub cmdEditMode_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst .Move 3 Debug.Print "EditMode before editing: " & .EditMode .Edit Debug.Print "EditMode after Edit : " & .EditMode !Description = "New description of this category" .Update Debug.Print "EditMode after updating: " & .EditMode .AddNew Debug.Print "EditMode after AddNew: " & .EditMode .CancelUpdate Debug.Print "EditMode after canceling editing: " & .EditMode .Close End With End Sub
| EOF |  |
|
Data Type
Boolean
Description
The EOF property (derived from "End of File") indicates that the current record position is after the last record in a recordset. It is useful for determining whether you have gone beyond the end of the records in a recordset when moving forward. In a recordset with no objects, this property is True. However, if you delete the last remaining record in a recordset, EOF may remain False until you attempt to reposition the record. See Table 8-5 in the BOF section for a summary of what happens when you use the Move methods with different combinations of the BOF and EOF properties, and Table 8-6 for a listing of what happens to the BOF and EOF properties after using Move methods that don't find a record.
VBA Code
This code uses the EOF marker to prevent going beyond the last record when iterating through a recordset:
Private Sub cmdEOF_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim fld As Field strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst Do While Not .EOF Debug.Print !CategoryName .MoveNext Loop .Close End With End Sub
Filter
Data Type
String
Description
Sets or returns a value that filters the records in a recordset (for Jet workspaces only). Basically, it is the WHERE clause of a SQL statement without the word WHERE. You can use Filter with dynaset-, snapshot-, or forward-only-type recordsets.
TIP:
After using the Filter property with a recordset, you don't see the results of filtering immediately--you must open another recordset from the filtered recordset to see the results.
VBA Code
This code sample illustrates using the Filter property to filter records by country, opening a second recordset of UK employees based on the original, unfiltered recordset:
Private Sub cmdFilter_Click() Dim dbs As Database Dim strDBName As String Dim rstEmployees As Recordset Dim rstUKEmployees As Recordset Dim strSearch As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rstEmployees = dbs.OpenRecordset("Employees", dbOpenDynaset) 'Create a filtered recordset based on the first recordset rstEmployees.Filter = "Country = 'UK'" Set rstUKEmployees = rstEmployees.OpenRecordset() With rstUKEmployees Debug.Print vbCrLf & "Filtered recordset:" Do While Not .EOF Debug.Print "Name: " & !LastName & ", country: " & !Country .MoveNext Loop End With End Sub
TIP:
Using the Filter property on a recordset is generally less efficient than just applying a filter to a recordset and opening it in one step, using a SQL statement with a WHERE clause.
Index
Data Type
String
Description
Sets or returns the name of the index to use for a table-type recordset in a Jet workspace. It must be the name of an existing index in the Indexes collection of the TableDef object that is the data source of the Recordset object. The Index property is used with the Seek method for locating records in an indexed recordset. See the Seek section later in this chapter for an example of usage.
| LastModified |  |
|
Data Type
Variant array of Byte data
Description
Returns a bookmark indicating which record in a recordset was most recently added or modified. It applies to table-type or dynaset-type recordsets only. The primary use of this property is to return to the record that was most recently modified in code by setting the Bookmark property equal to LastModified.
TIP:
The value of LastModified only reflects changes made to the recordset itself; if a record was changed in the interface or directly in the table, this change is not reflected in the LastModified property.
VBA Code
This code loops through tblCustomers (a copy of the Northwind Customers table), modifying records that meet a criterion, and then returns to the last modified record. I'm using the RecordCount property (-1) to avoid being at the EOF marker after looping; otherwise, there would be an error on the first Debug.Print line:
Private Sub cmdLastModified_Click() Dim dbs As Database Dim rst As Recordset Dim strTable As String Dim intCount As Integer Dim i As Integer strTable = "tblCustomers" Set dbs = CurrentDb Set rst = dbs.OpenRecordset(strTable, dbOpenTable) intCount = rst.RecordCount - 1 With rst For i = 1 To intCount If !Country = "UK" Then .Edit !Country = "United Kingdom" .Update Debug.Print "Changed " & !CompanyName & " record" End If .MoveNext Next i Debug.Print "After looping, at " & !CompanyName & " record" 'Go to most recently modified record .Bookmark = .LastModified Debug.Print "Last record modified: " & !CompanyName & " record" .Close End With End Sub
| LastUpdated |  |
|
Data Type
Date/Time
Description
Returns the date and time the recordset was last updated--in other words, when the data in the base table(s) was last changed. The changes can be made either in the interface or in code (unlike the LastModified property).
VBA Code
Private Sub cmdLastUpdated_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) Debug.Print "Date Created: " & rst.DateCreated Debug.Print "Last Updated: " & rst.LastUpdated End Sub
LockEdits
Data Type
Boolean
Description
For updatable recordsets the LockEdits property sets or returns a value indicating the type of locking in effect while editing, as shown in Table 8-8. Pessimistic locking (True) means that the page containing the record being edited is unavailable to other users until you are through editing and use the Update method to save the record. Optimistic locking (False) means that other users can access the same record you are working on, except just briefly while you are actually updating the record. Optimistic locking is more risky (two users can simultaneously change a record), but pessimistic locking may cause delays while records are unnecessarily locked.
Table 8-8: The LockEdits Values/Settings Named Constant | Value | Description |
|---|
True
| -1 | (Default) Pessimistic locking is in effect. The 2K page containing the record you're editing is locked as soon as you call the Edit method. |
False
| 0 | Optimistic locking is in effect for editing. The 2K page containing the record is not locked until the Update method is executed. |
TIP:
The LockEdits value can be preset by setting the lockedit argument of the OpenRecordset method; setting the lockedit argument to dbPessimistic sets the LockEdits property to True, and setting it to any other value sets LockEdits to False. When working with ODBC data sources, LockEdits is always set to False, allowing only optimistic locking.
| Name |  |
|
Data Type
String
Description
For recordsets, the Name property is either the name of the underlying table or query, or, if the recordset is based on a SQL statement, the first 256 characters of the SQL statement. This makes the Name property unreliable as a means of referencing a particular recordset. To reference a recordset, just use the variable it was set with.
VBA Code
The code lists the names of several recordsets created based on a table, a query, and a SQL statement:
Private Sub cmdName_Click() Dim dbs As Database Dim rstTable As Recordset Dim rstQuery As Recordset Dim rstSQL As Recordset Dim rst As Recordset Dim strDBName As String Dim intCount As Integer Dim strTable As String Dim strQuery As String Dim strSQL As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) strTable = "Orders" strQuery = "Ten Most Expensive Products" strSQL = "SELECT * FROM Customers" Set rstTable = dbs.OpenRecordset(strTable, dbOpenTable) Set rstSQL = dbs.OpenRecordset(strSQL, dbOpenSnapshot) Set rstQuery = dbs.OpenRecordset(strQuery, dbOpenSnapshot) For Each rst In dbs.Recordsets Debug.Print rst.Name Next rst End Sub
| NoMatch |  |
|
Data Type
Boolean
Description
Indicates whether a search was successful. It applies to searches done with the Seek method or one of the Find methods.
If a search is unsuccessful (NoMatch = True), the current record will no longer be valid. To avoid problems, save the record's bookmark to a variable so you can return to it after an unsuccessful search, as in the code sample in the Seek section.
PercentPosition
Data Type
Single
Description
Sets or returns a value between 0 and 100, representing the position of the current record in a recordset. For dynaset- or snapshot-type recordsets, move to the last record before using this method to ensure an accurate record count. The following code prints the percent position to the Debug window after each successful find of a record meeting a search criterion.
TIP:
You can use Percent Position with a scroll bar control on a form or text box to indicate the position of the current record in a recordset.
VBA Code
Private Sub cmdPercentPosition_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset Dim strSearch As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenSnapshot) strSearch = "[Title] = 'Sales Rep'" 'MoveLast to ensure an accurate count of records. With rst .MoveLast .MoveFirst .FindFirst strSearch Debug.Print !LastName & " record -- " & .PercentPosition & "%" .FindNext strSearch Debug.Print !LastName & " record -- " & .PercentPosition & "%" .Close End With dbs.Close End Sub
| RecordCount |  |
|
Data Type
Long
Description
Returns the number of records in a recordset. In case of dynaset-, snapshot-, or forward-only-type recordsets, you need to access all the records in the recordset before getting an accurate count of the records. See the following code sample for an example of usage of RecordCount for this purpose. This is not necessary for table-type recordsets.
VBA Code
Private Sub cmdRecordCount_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset Dim intCount As Integer strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenSnapshot) Debug.Print "Record count before traversing recordset: " & _ rst.RecordCount 'MoveLast to ensure an accurate count of records. rst.MoveLast Debug.Print "Record count after traversing recordset: " & _ rst.RecordCount rst.Close dbs.Close End Sub
| RecordStatus |  |
|
Data Type
Long
Description
Indicates the update status of the current record, if it is part of a batch update (for ODBCDirect workspaces only). The value returned indicates whether (and how) the current record will be involved in the next optimistic batch update. See Table 8-9 for a listing of the constants that may be returned.
Table 8-9: The RecordStatus Return Value Intrinsic Constants Named Constant | Value | Description |
|---|
dbRecordUnmodified
| 0 | (Default) The record has not been modified or has been updated successfully. |
dbRecordModified
| 1 | The record has been modified and not updated in the database. |
dbRecordNew
| 2 | The record has been inserted locally with the AddNew method, but not yet inserted into the database. |
dbRecordDeleted
| 3 | The record has been deleted locally, but not yet deleted in the database. |
dbRecordDBDeleted
| 4 | The record has been deleted locally and in the database. |
| Restartable |  |
|
Data Type
Boolean
Description
Indicates whether a recordset supports the Requery method. If the value is True, Requery can be used to re-execute the query on which the recordset is based; if it is False, the query can't be re-executed.
VBA Code
The following code opens three different types of recordsets, examines the Restartable property of each, and requeries those that are restartable:
Private Sub cmdRestartable_Click() Dim dbs As Database Dim rstTable As Recordset Dim rstQuery As Recordset Dim rstSQL As Recordset Dim rst As Recordset Dim strDBName As String Dim intCount As Integer Dim strTable As String Dim strQuery As String Dim strSQL As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) strTable = "Orders" strQuery = "Ten Most Expensive Products" strSQL = "SELECT * FROM Customers" Set rstTable = dbs.OpenRecordset(strTable, dbOpenTable) Set rstSQL = dbs.OpenRecordset(strSQL, dbOpenSnapshot) Set rstQuery = dbs.OpenRecordset(strQuery, dbOpenSnapshot) 'Determine whether each recordset is restartable, 'and requery it if so. For Each rst In dbs.Recordsets Debug.Print rst.Name & " restartable? " & rst.Restartable If rst.Restartable = True Then rst.Requery Next rst End Sub
Sort
Data Type
String
Description
Sets or returns the sort order for records in a recordset (for Jet workspaces only). Basically, it is the ORDER BY clause of a SQL statement without the phrase ORDER BY. You can use Sort with dynaset- and snapshot-type recordsets only. As with the Filter property, the Sort property only takes effect when a new recordset is created from the sorted recordset. The Sort property overrides any sort order that might be specified for a QueryDef on which a recordset is based.
TIP:
Using the Sort property on a recordset is generally less efficient than just applying a sort order to a recordset and opening it in one step, using a SQL statement with an ORDER BY clause.
VBA Code
The following code applies a Sort order to a recordset and then opens a second recordset based on the sorted original recordset:
Private Sub cmdSort_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset Dim rstSort As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenDynaset) rst.Sort = "Region" Set rstSort = rst.OpenRecordset With rstSort Do Until .EOF Debug.Print "State: " & !Region & " for "; !LastName .MoveNext Loop End With End Sub
| StillExecuting |  |
|
Data Type
Boolean
Description
For ODBCDirect workspaces only, indicates whether an asynchronous operation (one called with the dbRunAsync option) has finished executing. The return value is True if the query is still executing and False if it has finished executing. The Cancel method can be called to cancel execution if the value is True.
| Transactions |  |
|
Data Type
Boolean
Description
This property is True if the recordset supports transactions, and False if it does not. For ODBC workspaces the Transactions property indicates whether the ODBC driver supports transactions. The property can be used for dynaset- or table-type recordsets in Jet workspaces; for snapshot- and forward-only-type recordsets in Jet workspaces, it is always False. For dynaset- or table-type recordsets in Jet workspaces, the Transactions property is always True, indicating that you can use transactions.
TIP:
You should always check the Transactions property and make sure it returns True before working with transactions using the BeginTrans, CommitTrans, and Rollback methods.
VBA Code
This code creates a recordset from the QueryDefs in Northwind and lists the Transactions value for each one:
Private Sub cmdTransactions_Click() Dim dbs As Database Dim strDBName As String Dim qdf As QueryDef Dim rst As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Debug.Print "QueryDefs in " & dbs.Name For Each qdf In dbs.QueryDefs On Error Resume Next Set rst = dbs.OpenRecordset(qdf.Name) Debug.Print "Recordset name and type: " & rst.Name & vbTab & _ rst.Type Debug.Print "Transactions possible?: " & rst.Transactions Next qdf dbs.Close End Sub
| Type |  |
|
Data Type
Integer
Description
Indicates the recordset type of a Recordset object. The possible values are listed in Table 8-10.
Table 8-10: The Type Setting Return Values Intrinsic Constants Named Constant | Value | Description |
|---|
dbOpenTable
| 1 | Table ( Jet workspaces only) |
dbOpenDynamic
| 16 | Dynamic (ODBC workspaces only) |
dbOpenDynaset
| 2 | Dynaset |
dbOpenSnapshot
| 4 | Snapshot |
dbOpenForwardOnly
| 96 | Forward-only |
Using the Type property on recordsets can be useful when you don't know what type the recordset is. Note that the recordset type is not the same as the QueryDef type. There are many more QueryDef type constants than Recordset constants, and the available constants are different for the two types of objects.
VBA Code
The following code sample lists the recordset type of recordsets based on all the queries in Northwind:
Private Sub cmdType_Click() Dim dbs As Database Dim strDBName As String Dim qdf As QueryDef Dim rst As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Debug.Print "QueryDefs in " & dbs.Name For Each qdf In dbs.QueryDefs Debug.Print "Query name and type: " & qdf.Name & vbTab & qdf.Type Set rst = dbs.OpenRecordset(qdf.Name) Debug.Print "Recordset name and type: " & rst.Name & vbTab & _ rst.Type Next qdf dbs.Close End Sub
| Updatable |  |
|
Data Type
Boolean
Description
Indicates whether a recordset can be changed or updated. If it is True, the recordset can be updated; if it is False, it can't be updated.
VBA Code
This code creates recordsets from all the Northwind queries and reports on whether they are updatable:
Private Sub cmdUpdatable_Click() Dim dbs As Database Dim strDBName As String Dim qdf As QueryDef Dim rst As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Debug.Print "QueryDefs in " & dbs.Name For Each qdf In dbs.QueryDefs On Error Resume Next Set rst = dbs.OpenRecordset(qdf.Name) Debug.Print "Recordset name and type: " & rst.Name & vbTab & _ rst.Type Debug.Print "Recordset updatable?: " & rst.Updatable Next qdf dbs.Close End Sub
UpdateOptions
Data Type
Long
Description
Indicates how the WHERE clause is constructed for each record during a batch update and whether the update should use an UPDATE statement or a DELETE followed by an INSERT (for ODBCDirect workspaces only). The UpdateOptions value can be any of the constants in Table 8-11.
Table 8-11: The UpdateOptions Return Value/Settings Intrinsic Constants Named Constant | Value | Description |
|---|
dbCriteriaKey
| 1 | (Default) Uses just the key column(s) in the where clause. |
dbCriteriaModValues
| 2 | Uses the key column(s) and all updated columns in the where clause. |
dbCriteriaAllCols
| 4 | Uses the key column(s) and all the columns in the where clause. |
dbCriteriaTimeStamp
| 8 | Uses just the timestamp column if available (will generate a run-time error if no timestamp column is in the result set). |
dbCriteriaDeleteInsert
| 16 | Uses a set of DELETE and INSERT statements for each modified row. |
dbCriteriaUpdate
| 32 | (Default) Uses an UPDATE statement for each modified row. |
| ValidationRule |  |
|
Data Type
String
Description
Returns a value used to validate data as it is being changed or added to a field in a recordset's underlying data source table. It only applies to Jet workspaces. The ValidationRule phrase describes a comparison in the form of a SQL WHERE clause without the WHERE keyword. If the data does not meet the validation criteria, a trappable run-time error is generated, and the error message contains the text of the ValidationText property, if specified, or else the text of the expression specified by the ValidationRule property. See the ValidationRule section in Chapter 10, TableDefs Collection and TableDef Object, for more information on this property.
TIP:
ValidationRule comparison strings are limited to referencing the field; they can't contain references to user-defined functions or queries.
VBA Code
This code lists the fields in the Northwind Customers table and their validation rules and validation text, if any:
Private Sub cmdValidationRule_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim fld As Field strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst .MoveLast For Each fld In .Fields Debug.Print fld.Name If fld.ValidationRule <> "" Then Debug.Print "Validation Rule: " & fld.ValidationRule Debug.Print "Validation Text: " & fld.ValidationText End If Next fld .Close End With End Sub
| ValidationText |  |
|
Data Type
String
Description
The ValidationText property returns a value specifying the text of the message that appears when data for a field fails the validation rule specified by the ValidationRule property. It applies only to Jet workspaces. See the ValidationText section in Chapter 10 for more information on this property. See the code sample in the ValidationRule section for an example of usage of this property.
Recordset Object Methods
Table 8-12 summarizes the Recordset type supported by each method and whether it applies to Jet ( J) or ODBCDirect (O) workspaces, or both ( JO). A blank cell indicates that the property does not apply to either type of workspace.
Table 8-12: Recordset Method Summary Method | Table | Dynaset | Snapshot | Forward-Only | Dynamic |
|---|
AddNew | J | JO | O | O | O |
Cancel | | O | O | O | O |
CancelUpdate | J | JO | Oa | O | O |
Clone | J | J | J | | |
Close | J | JO | JO | JO | O |
CopyQueryDef | | J | J | J | |
Delete | J | JO | Oa | O | O |
Edit | J | JO | Oa | O | O |
FillCache | | J | | | |
FindFirst | | J | J | | |
FindLast | | J | J | | |
FindNext | | J | J | | |
FindPrevious | | J | J | | |
GetRows | J | JO | JO | JO | O |
Move | J | JO | JO | | O |
MoveFirst | J | JO | JO | | O |
MoveLast | J | JO | JO | | O |
MoveNext | J | JO | JO | JO | O |
MovePrevious | J | JO | JO | | O |
NextRecordset | | O | O | O | O |
OpenRecordset | J | J | J | | |
Requery | | JO | JO | JO | O |
Seek | J | | | | |
Update | J | JO | Oa | O | O |
The recordset types and their uses are listed in Table 8-13.
Table 8-13: Recordset Types and Their Uses Recordset Type | Usage |
|---|
Table | Represents a single base table. Supports the AddNew, Delete, and Seek methods, but not the Find* methods. ( Jet only.) |
Dynamic | Represents one or more base tables. Supports the AddNew and Delete methods, but not the Find* or Seek methods. |
Dynaset | Represents a table or an updatable query. Supports the AddNew, Delete, and Find* methods, but not the Seek method. |
Snapshot | A read-only recordset; useful for finding data or printing. Does not allow updating, except in the case of an updatable Snapshot in an ODBCDirect workspace. Supports the Find* methods. |
Forward-only | Similar to a snapshot, but only allows forward movement. Useful when you only need to make a single pass through a recordset. Does not support the Find* methods. |
AddNew
recordset.AddNew Adds a new record to an updatable recordset (table-type or dynaset recordsets only). For dynasets the new records are added at the end of the recordset. For indexed dynasets, the new record is placed in indexed order; if the dynaset is not indexed, the new record is added to the end of the recordset.
TIP:
Don't confuse AddNew and Append. The DAO AddNew method is the equivalent of Append in other database languages, such as dBASE, while the Append method in DAO is used to add new members to collections.
After adding a new record with the AddNew method, you need to use the Update method to save the new record, as in the following code sample. If you omit the Update, you won't get a warning, and the new record will be lost when you move to another record or close the recordset.
Note that in VBA code, you should use the dot (.) operator for recordset methods and properties, and the bang (!) operator for fields. In VBS code use the dot operator for methods, properties, and fields.
TIP:
If you get an "Item not found in this collection" error message when updating a recordset, it is probably the result of a misspelled field name (fields are members of the Fields collection within the recordset).
VBA Code
This code first lists the categories in the Northwind Categories table, then adds a new record, then lists the categories again, showing the newly added one:
Private Sub cmdAddNew_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) 'List categories before adding new record Debug.Print "Categories before adding new record:" & vbCrLf rst.MoveFirst Do Until rst.EOF Debug.Print rst!CategoryName rst.MoveNext Loop 'Add new category With rst .AddNew !CategoryName = "Dried Foods" !Description = _ "Freeze-dried and sun-dried fruits, vegetables, and meats" .Update End With 'List categories after adding new record Debug.Print vbCrLf & "Categories after adding new record:" & vbCrLf rst.MoveFirst Do Until rst.EOF Debug.Print rst!CategoryName rst.MoveNext Loop rst.Close End Sub
Cancel
recordset.Cancel Cancels execution of a pending asynchronous method call. It only applies to recordsets in ODBCDirect workspaces since it requires use of the dbRunAsync value for the MoveLast method's Options argument. See the StillExecuting section for an example that uses this method.
CancelUpdate
recordset.CancelUpdate updatetype Argument | Data Type | Description |
|---|
recordset | Recordset object | The Recordset object for which you are canceling pending updates |
updatetype | Integer | A named constant or Integer value (see Table 8-14) |
Cancels any pending updates for a Recordset object, such as would result from use of the Edit or AddNew methods. Before using the CancelUpdate method, you should check the EditMode property of the recordset to find out if there is a pending operation that can be canceled.
Table 8-14: The UpdateType Intrinsic Constants Named Constant | Value | Description |
|---|
dbUpdateRegular
| 1 | (Default) Cancels pending changes that aren't cached |
dbUpdateBatch
| 4 | Cancels pending changes in the update cache |
TIP:
The type argument settings in Table 8-14 can only be used if batch updating is enabled. In an ODBCDirect workspace (only), this is done by setting the DefaultCursorDriver property to dbUseClientBatchCursor when the connection is opened, and the recordset must be opened using OpenRecordset with the locktype argument set to dbOptimisticBatch .
VBA Code
This code illustrates the use of CancelUpdate to allow a user to confirm adding a new record to the Categories table in the Northwind database:
Private Sub cmdCancelUpdate_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset Dim intReturn As Integer Dim strCategory As String Dim strDescription As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Categories") With rst .AddNew strCategory = "Test" strDescription = "Test new food category" !CategoryName = strCategory !Description = strDescription intReturn = MsgBox("Add " & strCategory & " -- " & _ strDescription & " as a food category?", vbYesNo) If intReturn = VbYes Then .Update MsgBox strCategory & " -- " & strDescription & _ " added as a food category" Else .CancelUpdate MsgBox strCategory & " -- " & strDescription & _ " not added as a food category" End If End With End Sub
Clone
Set duplicate = original.Clone Argument | Data Type | Description |
|---|
duplicate | Recordset object | The duplicate Recordset object being created |
original | Recordset object | The original Recordset object being duplicated |
Creates a duplicate Recordset object that references the original Recordset object. The original and duplicate recordsets can have different current records. (Note, though, that after the cloning operation, the duplicate recordset initially has no current record.) Using the Clone method allows you to share bookmarks between Recordset objects, since their bookmarks are interchangeable.
VBA Code
This code sets up a recordset based on the Northwind Categories table, then clones it, and moves to different records in the original and duplicate recordsets:
Private Sub cmdClone_Click() Dim dbs As Database Dim strDBName As String Dim rstO As Recordset Dim rstD As Recordset Dim strSearch As String Dim strText As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rstO = dbs.OpenRecordset("Categories", dbOpenDynaset) Set rstD = rstO.Clone strText = "Dried Food" strSearch = "[CategoryID] = 2" rstO.FindFirst strSearch strSearch = "[CategoryID] = 8" rstD.FindFirst strSearch 'Report on where pointer is in the two recordsets. Debug.Print "At "; rstO!CategoryName & " record in original recordset" Debug.Print "At "; rstD!CategoryName & _ " record in duplicate recordset" rstO.Close rstD.Close dbs.Close End Sub
Close
recordset.Close Closes a recordset. You should always use this method to close a recordset before closing a database, because otherwise your pending edits and updates will be canceled.
TIP:
If you try to close a recordset that has already been closed, run-time error 3420, "Object invalid or no longer set," occurs.
See the code sample in the Clone section for an example of usage.
CopyQueryDef
Set querydef = recordset.CopyQueryDef Argument | Data Type | Description |
|---|
querydef | QueryDef object | The QueryDef object you want to create |
recordset | Recordset object | The Recordset object you are creating |
Returns a QueryDef object that is a copy of the QueryDef object originally used to create the Recordset object. A recordset must be created using the OpenRecordset method before using the CopyQueryDef method. This method can only be used in Jet workspaces. CopyQueryDef can be useful when you need to recreate a QueryDef from a recordset passed to a procedure.
WARNING:
An error occurs if you use this method on a recordset that was not based on a QueryDef.
VBA Code
The cmdCopyQueryDef_Click event procedure calls the CreateRecordset function, which sets a recordset variable, rst. (Note that the rst recordset variable is declared in the Declarations section of the module to make it public in scope.) When control returns to the event procedure, the CopyQueryDef method is used to recreate the QueryDef. The contents of one of the QueryDef's fields are then listed to the Debug window:
Private Function CreateRecordset() Dim dbs As Database Dim strDBName As String Dim qdf As QueryDef strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set qdf = dbs.QueryDefs("Sales by Category") Set rst = qdf.OpenRecordset End Function Private Sub cmdCopyQueryDef_Click() Dim qdf As QueryDef Call CreateRecordset Set qdf = rst.CopyQueryDef With rst Do While Not .EOF Debug.Print !CategoryName .MoveNext Loop .Close End With End Sub
Delete
recordset.Delete Deletes the current record from an updatable recordset. If the deleted record is in the primary table in a relationship set to permit cascading deletes, one or more records in the related table may also be deleted. The deleted record remains current (although it can't be edited or used) until you move to another record. It is not necessary to use Update after calling the Delete method.
TIP:
If you want to be able to undo deletions, you can use transactions and the Rollback method. Transactions are covered in Chapter 4, Workspaces Collection and Workspace Object .
VBA Code
This code goes to the last record in a recordset and deletes it:
Private Sub cmdDelete_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim intCount As Integer strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) intCount = rst.RecordCount Debug.Print intCount & " records in recordset" With rst .MoveLast .Delete intCount = .RecordCount .Close End With Debug.Print intCount & " records in recordset (after delete)" End Sub
Edit
recordset.Edit The Edit method prepares a record in an updatable recordset for editing by placing it in a temporary copy buffer. Generally, you must use the Edit method before making any changes to a record; however, the AddNew and Delete methods are exceptions (no need to use Edit before using either of them). After making changes to a record, you need to use the Update method to save the record.
TIP:
You must have a current record in order to use the Edit method.
WARNING:
If you edit a record and don't use the Update method to save the changes, they will be lost without warning or an error message when you close the recordset or move to another record.
VBA Code
Private Sub cmdEdit_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenTable) With rst .MoveLast Debug.Print "Description value before editing: " & !Description .Edit !Description = "New description of this category" .Update Debug.Print "Description value after editing: " & !Description .Close End With End Sub
FillCache
recordset.FillCache rows, startbookmark Argument | Data Type | Description |
|---|
recordset | Recordset object | A Recordset object created from an ODBC data source, such as a TableDef representing a linked table. |
rows | Integer | The number of rows to store in the cache (if omitted, the CacheSize property value is used). |
startbookmark | String | The Bookmark specifying the record from which the cache is filled (if omitted, the CacheStart property setting is used). |
For Jet-connected ODBC data sources only, this method fills all or part of a recordset's local cache. Caching can improve performance, as data can be retrieved faster from the local cache than from the remote data source.
VBA Code
The following VBA code compares the performance when iterating through a recordset based on a linked table, with or without caching. According to Help, performance should be better with caching, but when I ran this code with a table linked to Northwind, the time was actually slightly longer with caching.
Private Sub cmdFillCache_Click() Dim dbs As Database Dim rst As Recordset Dim strTable As String Dim sngStart As Single Dim sngEnd As Single Dim sngNoCache As Single Dim sngCache As Single Dim intCount As Integer Dim strTemp As String 'Set up a recordset based on a linked table. strTable = "tblContacts" Set dbs = CurrentDb Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) 'Iterate through recordset and time the operation. With rst .MoveFirst Do While Not .EOF sngStart = Timer strTemp = !LastName .MoveNext Loop sngEnd = Timer sngNoCache = sngEnd 'Display performance results. Debug.Print "Without cache: " & Format(sngNoCache, "##0,000.000") _ & " seconds" 'Cache the first 100 records and time the operation again. intCount = 0 .MoveFirst .CacheSize = 100 .FillCache sngStart = Timer .MoveFirst Do While Not .EOF strTemp = !LastName intCount = intCount + 1 .MoveNext If intCount Mod 100 = 0 Then On Error Resume Next .CacheStart = .Bookmark .FillCache End If Loop sngEnd = Timer sngCache = sngEnd 'Display performance results. Debug.Print "With cache: " & Format(sngCache, "##0,000.000") _ & " seconds" .Close End With End Sub
FindFirst
recordset.FindFirst criteria Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing dynaset-type or snapshot-type Recordset object |
criteria | String | A search string used to locate a record, similar to the WHERE clause in a SQL statement, but without the word WHERE |
For Jet workspaces only, the FindFirst method locates the first record in a dynaset or snapshot-type recordset that meets the specified criteria and makes that record the current record. If no matching record is found, the NoMatch property is set to True, making this property useful in determining the success or failure of the FindFirst method, as shown in the following code sample.
TIP:
To locate a record in a table-type recordset, use the Seek method instead of the FindFirst method.
VBA Code
Private Sub cmdFindFirst_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim strSearch As String Dim strName As String strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) strName = Chr(39) & "Smith" & Chr(39) strSearch = "[LastName] = " & strName With rst .FindFirst strSearch Debug.Print strName & " found? " & Not .NoMatch .Close End With End Sub
FindLast
recordset.FindLast criteria Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing dynaset-type or snapshot-type Recordset object |
criteria | String | A search string used to locate a record, similar to the WHERE clause in a SQL statement, but without the word WHERE |
Similar to the FindFirst method, for Jet workspaces only, the FindLast method locates the last record in a dynaset or snapshot-type recordset that meets the specified criteria and makes that record the current record. If no matching record is found, the NoMatch property is set to True.
VBA Code
Private Sub cmdFindLast_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim strSearch As String Dim strName As String strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) strName = Chr(39) & "Davolio" & Chr(39) strSearch = "[LastName] = " & strName With rst .FindLast strSearch Debug.Print strName & " found? " & Not .NoMatch .Close End With End Sub
FindNext
recordset.FindNext criteria Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing dynaset-type or snapshot-type Recordset object |
criteria | String | A search string used to locate a record, similar to the WHERE clause in a SQL statement, but without the word WHERE |
For Jet workspaces only, the FindNext method locates the next record in a dynaset or snapshot-type recordset that meets the specified criteria and makes that record the current record. If no matching record is found, the NoMatch property is set to True, so you can use this property to tell whether the method was successful in locating another match, as shown in the following code sample.
VBA Code
Private Sub cmdFindNext_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim strSearch As String Dim strTitle As String strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) strTitle = Chr(39) & "Sales Representative" & Chr(39) strSearch = "[Title] = " & strTitle With rst .FindFirst strSearch If .NoMatch = False Then Debug.Print "Found a match for " & strTitle & " -- name: " & _ !LastName End If .FindNext strSearch If .NoMatch = False Then Debug.Print "Found another match for " & strTitle & "--name: " _ & !LastName End If .Close End With End Sub
FindPrevious
recordset.FindPrevious criteria Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing dynaset-type or snapshot-type Recordset object |
criteria | String | A search string used to locate a record, similar to the WHERE clause in a SQL statement, but without the word WHERE |
FindPrevious works much like FindNext, except that it moves backward through the recordset instead of forward.
VBA Code
Private Sub cmdFindPrevious_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim strSearch As String Dim strTitle As String strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) strTitle = Chr(39) & "Sales Representative" & Chr(39) strSearch = "[Title] = " & strTitle With rst .FindFirst strSearch If .NoMatch = False Then Debug.Print "Found a match for " & strTitle & " -- name: " _ & !LastName End If .FindNext strSearch If .NoMatch = False Then Debug.Print "Found another match for " & strTitle & "--name: " _ & !LastName End If .FindPrevious strSearch If .NoMatch = False Then Debug.Print "Went back to last match for " & strTitle & _ " -- name: " & !LastName End If .Close End With End Sub
GetRows
Set varArray = recordset.GetRows(numrows) Argument | Data Type | Description |
|---|
varArray | Variant | An array that stores the retrieved rows of data |
recordset | Recordset object | A Recordset object |
numrows | Variant | The number of rows to retrieve (if left blank, all available rows are retrieved) |
Retrieves multiple rows from a Recordset object into a two-dimensional array. It is very useful for filling list boxes and combo boxes on Outlook forms or Office UserForms from Access tables since they can't be bound to tables or recordsets, unlike Access controls. See the VBS code sample and the second VBA sample for examples of this usage. If you want to retrieve just one field value from the array, you can specify the array element, as in the first VBA code sample (bear in mind that the array numbering is zero-based).
Access VBA Code
Private Sub cmdGetRows_Click() Dim dbs As Database Dim rst As Recordset Dim strTable As String Dim strFieldValue As String Dim varRecords As Variant Dim intRecord As Integer Dim intField As Integer strTable = "Employees" Set dbs = CurrentDb Set rst = dbs.OpenRecordset(strTable, dbOpenSnapshot) varRecords = rst.GetRows(10) Debug.Print "Fourth field in fifth record: " & varRecords(5, 6) End Sub
Outlook VBS Code
Sub cmdFillListBox_Click Dim rst Dim dao Dim wks Dim dbs Dim strAccessDir Dim objAccess Dim CustomerArray(99, 2) 'Pick up path to Access database directory from Access SysCmd function. Set objAccess = Item.Application.CreateObject("Access.Application") strAccessDir = objAccess.SysCmd(9) strDBName = strAccessDir & "Samples\Northwind.mdb" objAccess.Quit 'Set up reference to Access database. Set dao = Application.CreateObject("DAO.DBEngine.35") Set wks = dao.Workspaces(0) Set dbs = wks.OpenDatabase(strDBName) 'Retrieve Customer information from table. Set rst = dbs.OpenRecordset("Customers") Set ctl = Item.GetInspector.ModifiedFormPages("Message").Controls("lstCustomers") ctl.ColumnCount = 3 ctl.ColumnWidths = "50; 150 pt; 75 pt" 'Assign Access data to an array of 3 columns and 100 rows. CustomerArray(99, 2) = rst.GetRows(100) ctl.Column() = CustomerArray(99, 2) End Sub
VBA Code Behind an Office UserForm
This code runs from the Initialize event of an Office UserForm, so that the lstCustomers listbox is filled with data from Northwind when the form is run. The UserForm could be run from Word 97 or 2000, Excel 97 or 2000, or Outlook 2000:
Private Sub UserForm_Initialize() Dim dao As Object Dim rst As Recordset Dim wks As Workspace Dim dbs As Database Dim strDBName As String Dim strAccessDir As String Dim objAccess As New Access.Application Dim CustomerArray(99, 2) Dim ctl As ListBox 'Pick up path to Access database directory from Access SysCmd function. strAccessDir = objAccess.SysCmd(9) strDBName = strAccessDir & "Samples\Northwind.mdb" objAccess.Quit 'Set up reference to Access database. Set dao = CreateObject("DAO.DBEngine.35") Set wks = dao.Workspaces(0) Set dbs = wks.OpenDatabase(strDBName) 'Retrieve Customer information from table. Set rst = dbs.OpenRecordset("Customers") Set ctl = lstCustomers ctl.ColumnCount = 3 ctl.ColumnWidths = "50; 150 pt; 75 pt" 'Assign Access data to an array of 3 columns and 100 rows. CustomerArray(99, 2) = rst.GetRows(100) ctl.Column() = CustomerArray(99, 2) End Sub
Move
recordset.Move rows, startbookmark Argument | Data Type | Description |
|---|
recordset | Recordset object | The Recordset object whose current record position is being moved. |
rows | Long | The number of rows to move. If rows is greater than zero, the movement is forward; if it is negative, the movement is backward. |
startbookmark | String | The Bookmark of the record to start movement from. If omitted, Move begins from the current record. |
Moves the current position in a recordset, either forward or backward. If you are at the BOF marker and move backward or at the EOF marker and move forward, you will get an error. You will also get a run-time error if you try to use the Move method when either the BOF or EOF property is True. (See the BOF and EOF property sections for an explanation of these properties.)
VBA Code
This VBA code moves to the last record in a recordset, then back three records:
Private Sub cmdMove_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String strTable = "Employees" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) With rst .MoveLast .Move -3 Debug.Print "On " & !LastName & " record" .Close End With End Sub
MoveFirst
recordset.MoveFirst Moves to the first record in a recordset and makes it the current record. It is often used before a loop that iterates through the records in a recordset to ensure that the loop starts with the first record, as in the code sample in the FillCache section.
WARNING:
If you have edited the current record, before moving to another record, be sure to save the changes with the Update method; otherwise, the changes will be lost with no warning.
MoveLast
recordset.MoveLast Moves to the last record in a recordset and makes it the current record.
TIP:
For dynaset- or snapshot-type recordsets, you need to use the MoveLast method before counting the number of records in a recordset in order to get an accurate count.
VBA Code
Private Sub cmdMoveLast_Click() Dim dbs As Database Dim rst As Recordset Dim strDBName As String Dim strTable As String Dim intCount As Integer strTable = "Categories" strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset(strTable, dbOpenDynaset) intCount = rst.RecordCount Debug.Print intCount & " records in recordset (before MoveLast)" With rst .MoveLast intCount = .RecordCount .Close End With Debug.Print intCount & " records in recordset (after MoveLast)" End Sub
MoveNext
recordset.MoveNext Moves to the next record in a recordset and makes it the current record. It is often used in looping structures in code. See the FillCache section for an example of usage.
MovePrevious
recordset.MovePrevious Moves to the previous record in a recordset and makes it the current record. Usage is similar to MoveNext, except for the direction of movement.
NextRecordset
Set boolean = recordset.NextRecordset Argument | Data Type | Description |
|---|
boolean | Boolean | True indicates that the next set of records is available in recordset; False indicates that there are no more records, and recordset is empty.
|
recordset | Recordset object | An existing Recordset object variable to which you want to return pending records. |
This method gets the next set of records (if any) returned by a multipart select query in an OpenRecordset call. It returns a Boolean value indicating whether there are any more additional records pending. The method only applies to ODBCDirect workspaces.
OpenRecordset
Set recordset = object.OpenRecordset(name, type, options, lockedit)Set recordset = object.OpenRecordset(type, options, lockedit) Argument | Data Type | Description |
|---|
recordset | Recordset object | The Recordset object to be opened. |
object | Connection, Database, Recordset, QueryDef, or TableDef object | The object from which the recordset is to be created. |
source | String | The record source for the new Recordset object. May be a table name, a query name, or a SQL statement. For table-type Jet recordsets, only table names are allowable. |
name | Integer | A named constant or Integer value defining the type of recordset to open (see Table 8-15). |
options | Long | A named constant or Long value (see Table 8-16). |
lockedit | Integer | A named constant or Integer value (see Table 8-17). |
WARNING:
A saved query or SQL statement used for the source argument must be a query that returns records, not an action query. If you specify an action query, an "Invalid Operation" error occurs.
Table 8-15: The Type Intrinsic Constants Named Constant | Value | Description |
|---|
dbOpenTable
| 1 | Opens a table-type Recordset object ( Jet workspaces only) |
dbOpenDynamic
| 16 | Opens a dynamic-type Recordset object, similar to an ODBC dynamic cursor (ODBCDirect workspaces only) |
dbOpenDynaset
| 2 | Opens a dynaset-type Recordset object, similar to an ODBC keyset cursor |
dbOpenSnapshot
| 4 | Opens a snapshot-type Recordset object similar to an ODBC static cursor |
dbOpenForwardOnly
| 8 | Opens a forward-only-type Recordset object |
Table 8-16: The Options Intrinsic Constants Named Constant | Value | Description |
|---|
dbAppendOnly
| 8 | Allows users to append new records to the Recordset, but prevents them from editing or deleting existing records ( Jet dynaset-type Recordset only). |
dbSQLPassThrough
| 64 | Passes a SQL statement to a Jet-connected ODBC data source for processing ( Jet snapshot-type Recordset only). |
dbSeeChanges
| 512 | Generates a run-time error if one user is changing data that another user is editing ( Jet dynaset-type Recordset only). This setting is useful in applications where multiple users have simultaneous read/write access to the same data. |
dbDenyWrite
| 1 | Prevents other users from modifying or adding records ( Jet Recordset objects only). |
dbDenyRead
| 2 | Prevents other users from reading data in a table ( Jet table-type Recordset only). |
dbForwardOnly
| 256 | Creates a forward-only Recordset ( Jet snapshot-type Recordset only). It is provided only for backward compatibility, and you should use the dbOpenForwardOnly constant in the type argument instead of using this option. |
dbReadOnly
| 4 | Prevents users from making changes to the Recordset ( Jet only). The dbReadOnly constant in the lockedit argument replaces this option, which is provided only for backward compatibility. |
dbRunAsync
| 1024 | Runs an asynchronous query (ODBCDirect workspaces only). |
dbExecDirect
| 2048 | Runs a query by skipping SQLPrepare and directly calling SQLExecDirect (ODBCDirect workspaces only). Use this option only when you're not opening a Recordset based on a parameter query. |
dbInconsistent
| 16 | Allows inconsistent updates ( Jet dynaset-type and snapshot-type Recordset objects only). |
dbConsistent
| 32 | Allows only consistent updates ( Jet dynaset-type and snapshot-type Recordset objects only). |
Table 8-17: The LockEdit Intrinsic Constants Named Constant | Value | Description |
|---|
dbReadOnly
| 4 | Prevents users from making changes to the Recordset (default for ODBCDirect workspaces). You can use dbReadOnly in either the options argument or the lockedit argument, but not both. If you use it for both arguments, a run-time error occurs. |
dbPessimistic
| 2 | Uses pessimistic locking to determine how changes are made to the Recordset in a multiuser environment. The page containing the record you're editing is locked as soon as you use the Edit method (default for Jet workspaces). |
dbOptimistic
| 3 | Uses optimistic locking to determine how changes are made to the Recordset in a multiuser environment. The page containing the record is not locked until the Update method is executed. |
dbOptimisticValue
| 1 | Uses optimistic concurrency based on row values (ODBCDirect workspaces only). |
dbOptimisticBatch
| 5 | Enables batch optimistic updating (ODBCDirect workspaces only). |
The OpenRecordset method creates a new recordset and automatically appends it to the Recordsets collection. The first syntax variant for the OpenRecordset method call applies to Connection and Database objects, and the second variant applies to QueryDef, Recordset, and TableDef objects. See the OpenRecordset section in Chapter 5, Databases Collection and Database Object, for a number of code samples illustrating use of this method with Database objects in Access VBA, Word VBA, Excel VBA, and Outlook VBS code.
VBA Code
This code opens a filtered recordset based on another recordset and displays the results to the Debug window:
Private Sub cmdOpenRecordset_Click() Dim dbs As Database Dim strDBName As String Dim rstEmployees As Recordset Dim rstWAEmployees As Recordset Dim strSearch As String strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rstEmployees = dbs.OpenRecordset("Employees", dbOpenDynaset) With rstEmployees Debug.Print vbCrLf & "Unfiltered recordset:" Do While Not .EOF Debug.Print "Name: " & !LastName & ", state: " & !Region .MoveNext Loop End With 'Create a second, filtered recordset based on the first recordset. rstEmployees.Filter = "Region = 'WA'" Set rstWAEmployees = rstEmployees.OpenRecordset() With rstWAEmployees Debug.Print vbCrLf & "Filtered recordset:" Do While Not .EOF Debug.Print "Name: " & !LastName & ", state: " & !Region .MoveNext Loop End With End Sub
Requery
recordset.Requery newquerydef Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing Jet dynaset-, snapshot-, or forward-only Recordset object, or an ODBCDirect Recordset object |
newquerydef | Variant | (Optional) The Name property of a QueryDef object ( Jet workspaces only) |
The Requery method updates the data in a recordset by re-executing the query on which it is based. The newquerydef argument can be used to specify a new query for the recordset.
WARNING:
When you use the Requery method, the first record in the recordset becomes the current record, which can be a problem on forms. To avoid losing the user's place on a form after requerying, you can set a search string before requerying so you can return to the record you were on, as in the following code sample.
VBA Code
This code runs from a command button on an Access form; it calls a function (Calcinome, not reproduced here) that modifies data in the form's record source, so that the form needs requerying:
Private Sub cmdRequery_Click() Dim strSearch As String Dim strContract As String 'Create search string for current record. strContract = Me![ContractNo] strSearch = "[ContractNo] = " & strContract 'Call a function that needs requerying. Call Calcincome Me.Requery 'Find the record that matches the control. Debug.Print "Search string: " & strSearch Me.RecordsetClone.FindFirst strSearch Me.Bookmark = Me.RecordsetClone.Bookmark End Sub
Seek
recordset.Seek comparison, key1, key2...key13 Argument | Data Type | Description |
|---|
recordset | Recordset object | An existing table-type Recordset object with an index specified by the Recordset object's Index property |
comparison | String | One of the following expressions: <, <=, =, >=, or > |
key1, key2..., key13 | | One or more values (up to 13 in number) corresponding to fields in the Recordset object's current index, as specified by its Index property |
For indexed table-type recordsets in Jet workspaces, the Seek method locates a record that meets the criteria for the current index and makes it the current record. You must set the Index property to the index you want to use before using Seek. (You can also determine if the index you want is active by retrieving its value beforehand.) If the index identifies a nonunique key field, Seek locates the first record that satisfies the criteria.
For =, >=, and > comparisons, Seek starts at the beginning of the index and seeks forward; for <>
You must specify values for all fields defined in the index in order to use Seek.
The key1 argument must be of the same field data type as the corresponding field in the current index.
Seek can be used even if there is no current record. You can't use Seek on a linked table, because you can't create a table-type recordset on a linked table.
See the Index property section for more information about indexes.
VBA Code
Private Sub cmdSeek_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset Dim varBookmark As Variant Dim intEmployee As Integer strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenTable) With rst .Index = "PrimaryKey" 'Bookmark current record so we can return to it later. varBookmark = .Bookmark intEmployee = InputBox("Enter an Employee ID:") .Seek "=", intEmployee 'Return to current record if Seek fails. If .NoMatch Then MsgBox "ID " & intEmployee & " not found" .Bookmark = varBookmark Else MsgBox "Found ID at " & !LastName & " record" End If .Close End With End Sub
Update
recordset.Update(updatetype, force) Argument | Data Type | Description |
|---|
recordset | Recordset object | An open, updatable Recordset object. |
updatetype | Integer | A named constant or Integer value (see Table 8-18) (for ODBCDirect workspaces only). |
force | Boolean | (Optional) If True, force changes regardless of whether another user has made any changes. If False (default), the update fails if another user has made changes while the update is pending. |
Table 8-18: The UpdateType Intrinsic Constants Named Constant | Value | Description |
|---|
dbUpdateBatch
| 4 | All pending changes in the update cache are written to disk |
dbUpdateCurrentRecord
| 2 | Only the current record's pending changes are written to disk |
dbUpdateRegular
| 1 | (Default) Pending changes aren't cached and are written to disk immediately |
The Update method is crucial to saving your edits; it must be used for all edits done to a record, after creating a new record with AddNew, or calling the Edit method to edit an existing record. One exception is that you don't need to use Update after deleting a record with Delete. If you don't use Update after making a change (other than a Delete), the changes will be lost in any of the following situations:
- You use Edit or AddNew and move to another record without using Update.
- You use Edit or AddNew then use Edit or AddNew again without first using Update.
- You set the Bookmark property to another record.
- You close the recordset without first using Update.
- You cancel editing by using CancelUpdate.
VBA Code
This example code illustrates a standard use of the Update method after using the Edit method and making some changes to a record, in a looping structure that iterates through an entire recordset:
Private Sub cmdUpdate_Click() Dim dbs As Database Dim strDBName As String Dim rst As Recordset strDBName = "D:\Documents\Northwind.mdb" Set dbs = OpenDatabase(strDBName) Set rst = dbs.OpenRecordset("Employees", dbOpenTable) With rst .MoveFirst Do While Not .EOF .Edit If !Title = "Sales Representative" Then !Title = "Sales Rep" .Update .MoveNext Loop .Close End With dbs.Close End Sub