Propiedad Workspace.DefaultCursorDriver (DAO)

Se aplica a: Access 2013, Office 2013

Sintaxis

expresión . DefaultCursorDriver

expression Variable que representa un objeto Workspace.

Comentarios

La configuración o el valor devuelto se puede establecer en una de las constantes CursorDriverEnum.

El valor de esta propiedad sólo afecta a las conexiones establecidas después de establecer la propiedad. El cambio de la propiedad DefaultCursorDriver no tiene efecto en las conexiones existentes.

Ejemplo

En este ejemplo se usa el método NextRecordset para ver los datos de una consulta SELECT compuesta. La propiedad DefaultCursorDriver debe estar establecida en dbUseODBCCursor al ejecutar estas consultas. El método NextRecordset devolverá True incluso si algunas o todas las instrucciones SELECT no devuelven registro alguno; devolverá False solo después de que se hayan comprobado todas las cláusulas SQL individuales.

    Sub NextRecordsetX() 
     
     Dim wrkODBC As Workspace 
     Dim conPubs As Connection 
     Dim rstTemp As Recordset 
     Dim intCount As Integer 
     Dim booNext As Boolean 
     
     ' Create ODBCDirect Workspace object and open Connection 
     ' object. The DefaultCursorDriver setting is required 
     ' when using compound SQL statements. 
     Set wrkODBC = CreateWorkspace("", _ 
     "admin", "", dbUseODBC) 
     wrkODBC.DefaultCursorDriver = dbUseODBCCursor 
     
     ' Note: The DSN referenced below must be set to 
     ' use Microsoft Windows NT Authentication Mode to 
     ' authorize user access to the Microsoft SQL Server. 
     Set conPubs = wrkODBC.OpenConnection("Publishers", , , _ 
     "ODBC;DATABASE=pubs;DSN=Publishers") 
     
     ' Construct compound SELECT statement. 
     Set rstTemp = conPubs.OpenRecordset("SELECT * " & _ 
     "FROM authors; " & _ 
     "SELECT * FROM stores; " & _ 
     "SELECT * FROM jobs") 
     
     ' Try printing results from each of the three SELECT 
     ' statements. 
     booNext = True 
     intCount = 1 
     With rstTemp 
     Do While booNext 
     Debug.Print "Contents of recordset #" & intCount 
     Do While Not .EOF 
     Debug.Print , .Fields(0), .Fields(1) 
     .MoveNext 
     Loop 
     booNext = .NextRecordset 
     Debug.Print " rstTemp.NextRecordset = " & _ 
     booNext 
     intCount = intCount + 1 
     Loop 
     End With 
     
     rstTemp.Close 
     conPubs.Close 
     wrkODBC.Close 
     
    End Sub 

Esta misma tarea se puede realizar también creando una instrucción preparada que contenga la instrucción SQL compuesta. La propiedad CacheSize del objeto QueryDef debe estar establecida en 1 y el objeto Recordset debe ser de sólo avance y de solo lectura.

Sub NextRecordsetX2() 
 
 Dim wrkODBC As Workspace 
 Dim conPubs As Connection 
 Dim qdfTemp As QueryDef 
 Dim rstTemp As Recordset 
 Dim intCount As Integer 
 Dim booNext As Boolean 
 
 ' Create ODBCDirect Workspace object and open Connection 
 ' object. The DefaultCursorDriver setting is required 
 ' when using compound SQL statements. 
 Set wrkODBC = CreateWorkspace("", _ 
 "admin", "", dbUseODBC) 
 wrkODBC.DefaultCursorDriver = dbUseODBCCursor 
 
 ' Note: The DSN referenced below must be set to 
 ' use Microsoft Windows NT Authentication Mode to 
 ' authorize user access to the Microsoft SQL Server. 
 Set conPubs = wrkODBC.OpenConnection("Publishers", , , _ 
 "ODBC;DATABASE=pubs;DSN=Publishers") 
 
 ' Create a temporary stored procedure with a compound 
 ' SELECT statement. 
 Set qdfTemp = conPubs.CreateQueryDef("", _ 
 "SELECT * FROM authors; " & _ 
 "SELECT * FROM stores; " & _ 
 "SELECT * FROM jobs") 
 ' Set CacheSize and open Recordset object with arguments 
 ' that will allow access to multiple recordsets. 
 qdfTemp.CacheSize = 1 
 Set rstTemp = qdfTemp.OpenRecordset(dbOpenForwardOnly, _ 
 dbReadOnly) 
 
 ' Try printing results from each of the three SELECT 
 ' statements. 
 booNext = True 
 intCount = 1 
 With rstTemp 
 Do While booNext 
 Debug.Print "Contents of recordset #" & intCount 
 Do While Not .EOF 
 Debug.Print , .Fields(0), .Fields(1) 
 .MoveNext 
 Loop 
 booNext = .NextRecordset 
 Debug.Print " rstTemp.NextRecordset = " & _ 
 booNext 
 intCount = intCount + 1 
 Loop 
 End With 
 
 rstTemp.Close 
 qdfTemp.Close 
 conPubs.Close 
 wrkODBC.Close 
 
End Sub 
 

En este ejemplo se usan las propiedades RecordStatus y DefaultCursorDriver para mostrar cómo se realiza el seguimiento de los cambios a un Recordset durante una actualización por lotes. Se requiere la función RecordStatusOutput para que pueda ejecutarse este procedimiento.

Sub RecordStatusX() 
 
 Dim wrkMain As Workspace 
 Dim conMain As Connection 
 Dim rstTemp As Recordset 
 
 Set wrkMain = CreateWorkspace("ODBCWorkspace", _ 
 "admin", "", dbUseODBC) 
 ' This DefaultCursorDriver setting is required for 
 ' batch updating. 
 wrkMain.DefaultCursorDriver = dbUseClientBatchCursor 
 
 ' Note: The DSN referenced below must be configured to 
 ' use Microsoft Windows NT Authentication Mode to 
 ' authorize user access to the Microsoft SQL Server. 
 Set conMain = wrkMain.OpenConnection("Publishers", _ 
 dbDriverNoPrompt, False, _ 
 "ODBC;DATABASE=pubs;DSN=Publishers") 
 
 ' The following locking argument is required for 
 ' batch updating. 
 Set rstTemp = conMain.OpenRecordset( _ 
 "SELECT * FROM authors", dbOpenDynaset, 0, _ 
 dbOptimisticBatch) 
 
 With rstTemp 
 .MoveFirst 
 Debug.Print "Original record: " & !au_lname 
 Debug.Print , RecordStatusOutput2(.RecordStatus) 
 
 .Edit 
 !au_lname = "Bowen" 
 .Update 
 Debug.Print "Edited record: " & !au_lname 
 Debug.Print , RecordStatusOutput2(.RecordStatus) 
 
 .AddNew 
 !au_lname = "NewName" 
 .Update 
 Debug.Print "New record: " & !au_lname 
 Debug.Print , RecordStatusOutput2(.RecordStatus) 
 
 .Delete 
 Debug.Print "Deleted record: " & !au_lname 
 Debug.Print , RecordStatusOutput2(.RecordStatus) 
 
 ' Close the local recordset without updating the 
 ' data on the server. 
 .Close 
 End With 
 
 conMain.Close 
 wrkMain.Close 
 
End Sub 
 
Function RecordStatusOutput(lngTemp As Long) As String 
 
 Dim strTemp As String 
 
 strTemp = "" 
 
 ' Construct an output string based on the RecordStatus 
 ' value. 
If lngTemp = dbRecordUnmodified Then _ 
 strTemp = "[dbRecordUnmodified]" 
 If lngTemp = dbRecordModified Then _ 
 strTemp = "[dbRecordModified]" 
 If lngTemp = dbRecordNew Then _ 
 strTemp = "[dbRecordNew]" 
 If lngTemp = dbRecordDeleted Then _ 
 strTemp = "[dbRecordDeleted]" 
 If lngTemp = dbRecordDBDeleted Then _ 
 strTemp = "[dbRecordDBDeleted]" 
 
 RecordStatusOutput = strTemp 
 
End Function