Recordset Object

  • Article
Access Developer Reference

A Recordset object represents the records in a base table or the records that result from running a query.

Remarks

You use Recordset objects to manipulate data in a database at the record level. When you use DAO objects, you manipulate data almost entirely using Recordset objects. All Recordset objects are constructed using records (rows) and fields (columns). There are five types of Recordset objects:

  • Table-type Recordset— representation in code of a base table that you can use to add, change, or delete records from a single database table (Microsoft Access workspaces only).
  • Dynaset-type Recordset— the result of a query that can have updatable records. A dynaset-type Recordset object is a dynamic set of records that you can use to add, change, or delete records from an underlying database table or tables. A dynaset-type Recordset object can contain fields from one or more tables in a database. This type corresponds to an ODBC keyset cursor.
  • Snapshot-type Recordset— a static copy of a set of records that you can use to find data or generate reports. A snapshot-type Recordset object can contain fields from one or more tables in a database but can't be updated. This type corresponds to an ODBC static cursor.
  • Forward-only-type Recordset— identical to a snapshot except that no cursor is provided. You can only scroll forward through records. This improves performance in situations where you only need to make a single pass through a result set. This type corresponds to an ODBC forward-only cursor.
  • Dynamic-type Recordset— a query result set from one or more base tables in which you can add, change, or delete records from a row-returning query. Further, records other users add, delete, or edit in the base tables also appear in your Recordset. This type corresponds to an ODBC dynamic cursor (ODBCDirect workspaces only).
    Bb177501.vs_note(en-us,office.12).gif  Note
    ODBCDirect workspaces are not supported in Microsoft Office Access 2007. Use ADO if you want to access external data sources without using the Microsoft Access database engine.

You can choose the type of Recordset object you want to create using the type argument of the OpenRecordset method.

In a Microsoft Access workspace, if you don't specify a type, DAO attempts to create the type of Recordset with the most functionality available, starting with table. If this type isn't available, DAO attempts a dynaset, then a snapshot, and finally a forward-only type Recordset object.

In an ODBCDirect workspace, if you don't specify a type, DAO attempts to create the type of Recordset with the fastest query response, starting with forward-only. If this type isn't available, DAO attempts a snapshot, then a dynaset, and finally a dynamic- type Recordset object.

When creating a Recordset object using a non-linked TableDef object in a Microsoft Access workspace, table-type Recordset objects are created. Only dynaset-type or snapshot-type Recordset objects can be created with linked tables or tables in Microsoft Access database engine-connected ODBC databases.

A new Recordset object is automatically added to the Recordsets collection when you open the object, and is automatically removed when you close it.

Bb177501.vs_note(en-us,office.12).gif  Note
If you use variables to represent a Recordset object and the Database object that contains the Recordset, make sure the variables have the same scope, or lifetime. For example, if you declare a public variable that represents a Recordset object, make sure the variable that represents the Database containing the Recordset is also public, or is declared in a Sub or Function procedure using the Static keyword.

You can create as many Recordset object variables as needed. Different Recordset objects can access the same tables, queries, and fields without conflicting.

Dynaset–, snapshot–, and forward–only–type Recordset objects are stored in local memory. If there isn't enough space in local memory to store the data, the Microsoft Access database engine saves the additional data to TEMP disk space. If this space is exhausted, a trappable error occurs.

The default collection of a Recordset object is the Fields collection, and the default property of a Field object is the Value property. Use these defaults to simplify your code.

When you create a Recordset object, the current record is positioned to the first record if there are any records. If there are no records, the RecordCount property setting is 0, and the BOF and EOF property settings are True.

You can use the MoveNext, MovePrevious, MoveFirst, and MoveLast methods to reposition the current record. Forward–only–type Recordset objects support only the MoveNext method. When using the Move methods to visit each record (or "walk" through the Recordset), you can use the BOF and EOF properties to check for the beginning or end of the Recordset object.

With dynaset- and snapshot-type Recordset objects in a Microsoft Access workspace, you can also use the Find methods, such as FindFirst, to locate a specific record based on criteria. If the record isn't found, the NoMatch property is set to True. For table-type Recordset objects, you can scan records using the Seek method.

The Type property indicates the type of Recordset object created, and the Updatable property indicates whether you can change the object's records.

Information about the structure of a base table, such as the names and data types of each Field object and any Index objects, is stored in a TableDef object.

To refer to a Recordset object in a collection by its ordinal number or by its Name property setting, use any of the following syntax forms:

Recordsets(0)

Recordsets("name")

Recordsets![name]

Bb177501.vs_note(en-us,office.12).gif  Note
You can open a Recordset object from the same data source or database more than once, creating duplicate names in the Recordsets collection. You should assign Recordset objects to object variables and refer to them by variable name.

Example

This example demonstrates Recordset objects and the Recordsets collection by opening four different types of Recordsets, enumerating the Recordsets collection of the current Database, and enumerating the Properties collection of each Recordset.

Visual Basic for Applications 
  Sub RecordsetX()

Dim dbsNorthwind As Database
Dim rstTable As Recordset
Dim rstDynaset As Recordset
Dim rstSnapshot As Recordset
Dim rstForwardOnly As Recordset
Dim rstLoop As Recordset
Dim prpLoop As Property


Set dbsNorthwind = OpenDatabase("Northwind.mdb")


With dbsNorthwind


  ' Open one of each type of Recordset object.
  Set rstTable = .OpenRecordset("Categories", _
     dbOpenTable)
  Set rstDynaset = .OpenRecordset("Employees", _
     dbOpenDynaset)
  Set rstSnapshot = .OpenRecordset("Shippers", _
     dbOpenSnapshot)
  Set rstForwardOnly = .OpenRecordset _ 
     ("Employees", dbOpenForwardOnly)

  Debug.Print "Recordsets in Recordsets " & _
     "collection of dbsNorthwind"

  ' Enumerate Recordsets collection.
  For Each rstLoop In .Recordsets

     With rstLoop
        Debug.Print "  " & .Name

        ' Enumerate Properties collection of each
        ' Recordset object. Trap for any 
        ' properties whose values are invalid in 
        ' this context.
        For Each prpLoop In .Properties
           On Error Resume Next
           If prpLoop <> "" Then Debug.Print _
              "    " & prpLoop.Name & _
              " = " & prpLoop
           On Error GoTo 0
        Next prpLoop

     End With

  Next rstLoop

  rstTable.Close
  rstDynaset.Close
  rstSnapshot.Close
  rstForwardOnly.Close

  .Close



End With


End Sub

This example uses the OpenRecordset method to open five different Recordset objects and display their contents. The OpenRecordsetOutput procedure is required for this procedure to run.

Visual Basic for Applications 
  Sub OpenRecordsetX()

Dim wrkAcc As Workspace
Dim wrkODBC As Workspace
Dim dbsNorthwind As Database
Dim conPubs As Connection
Dim rstTemp As Recordset
Dim rstTemp2 As Recordset


' Open Microsoft Access and ODBCDirect workspaces, Microsoft
' Access database, and ODBCDirect connection.
Set wrkAcc = CreateWorkspace("", "admin", "", dbUseJet)
Set wrkODBC = CreateWorkspace("", "admin", "", dbUseODBC)
Set dbsNorthwind = wrkAcc.OpenDatabase("Northwind.mdb")


' 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("", , , _
"ODBC;DATABASE=pubs;DSN=Publishers")


' Open five different Recordset objects and display the
' contents of each.


Debug.Print "Opening forward-only-type recordset " & _
"where the source is a QueryDef object..."
Set rstTemp = dbsNorthwind.OpenRecordset( _
"Ten Most Expensive Products", dbOpenForwardOnly)
OpenRecordsetOutput rstTemp


Debug.Print "Opening read-only dynaset-type " & _
"recordset where the source is an SQL statement..."
Set rstTemp = dbsNorthwind.OpenRecordset( _
"SELECT * FROM Employees", dbOpenDynaset, dbReadOnly)
OpenRecordsetOutput rstTemp


' Use the Filter property to retrieve only certain
' records with the next OpenRecordset call.
Debug.Print "Opening recordset from existing " & _
"Recordset object to filter records..."
rstTemp.Filter = "LastName >= 'M'"
Set rstTemp2 = rstTemp.OpenRecordset()
OpenRecordsetOutput rstTemp2


Debug.Print "Opening dynamic-type recordset from " & _
"an ODBC connection..."
Set rstTemp = conPubs.OpenRecordset( _
"SELECT * FROM stores", dbOpenDynamic)
OpenRecordsetOutput rstTemp


' Use the StillExecuting property to determine when the
' Recordset is ready for manipulation.
Debug.Print "Opening snapshot-type recordset based " & _
"on asynchronous query to ODBC connection..."
Set rstTemp = conPubs.OpenRecordset("publishers", _
dbOpenSnapshot, dbRunAsync)
Do While rstTemp.StillExecuting
Debug.Print "  [still executing...]"
Loop
OpenRecordsetOutput rstTemp


rstTemp.Close
dbsNorthwind.Close
conPubs.Close
wrkAcc.Close
wrkODBC.Close


End Sub


Sub OpenRecordsetOutput(rstOutput As Recordset)


' Enumerate the specified Recordset object.
With rstOutput
Do While Not .EOF
Debug.Print , .Fields(0), .Fields(1)
.MoveNext
Loop
End With


End Sub

This example opens a dynamic-type Recordset object and enumerates its records.

Visual Basic for Applications 
  Sub dbOpenDynamicX()

Dim wrkMain As Workspace
Dim conMain As Connection
Dim qdfTemp As QueryDef
Dim rstTemp As Recordset
Dim strSQL As String
Dim intLoop As Integer


' Create ODBC workspace and open connection to
' SQL Server database.
Set wrkMain = CreateWorkspace("ODBCWorkspace", _
"admin", "", dbUseODBC)


' 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")


' Open dynamic-type recordset.
Set rstTemp = _
conMain.OpenRecordset("authors", _
dbOpenDynamic)


With rstTemp
Debug.Print "Dynamic-type recordset: " & .Name


  ' Enumerate records.
  Do While Not .EOF
     Debug.Print "    " & !au_lname & ", " & _
        !au_fname
     .MoveNext
  Loop

  .Close



End With


conMain.Close
wrkMain.Close


End Sub

This example opens a dynaset-type Recordset and shows the extent to which its fields are updatable.

Visual Basic for Applications 
  Sub dbOpenDynasetX()

Dim dbsNorthwind As Database
Dim rstInvoices As Recordset
Dim fldLoop As Field


Set dbsNorthwind = OpenDatabase("Northwind.mdb")
Set rstInvoices = _
dbsNorthwind.OpenRecordset("Invoices", dbOpenDynaset)


With rstInvoices
Debug.Print "Dynaset-type recordset: " & .Name


  If .Updatable Then
     Debug.Print "  Updatable fields:"

     ' Enumerate Fields collection of dynaset-type
     ' Recordset object, print only updatable
     ' fields.
     For Each fldLoop In .Fields
        If fldLoop.DataUpdatable Then
           Debug.Print "    " & fldLoop.Name
        End If
     Next fldLoop

  End If

  .Close



End With


dbsNorthwind.Close


End Sub

This example opens a forward-only-type Recordset, demonstrates its read-only characteristics, and steps through the Recordset with the MoveNext method.

Visual Basic for Applications 
  Sub dbOpenForwardOnlyX()

Dim dbsNorthwind As Database
Dim rstEmployees As Recordset
Dim fldLoop As Field


Set dbsNorthwind = OpenDatabase("Northwind.mdb")
' Open a forward-only-type Recordset object. Only the
' MoveNext and Move methods may be used to navigate
' through the recordset.
Set rstEmployees = _
dbsNorthwind.OpenRecordset("Employees", _
dbOpenForwardOnly)


With rstEmployees
Debug.Print "Forward-only-type recordset: " & _
.Name & ", Updatable = " & .Updatable


  Debug.Print "  Field - DataUpdatable"
  ' Enumerate Fields collection, printing the Name and 
  ' DataUpdatable properties of each Field object.
  For Each fldLoop In .Fields
     Debug.Print "    " & _
        fldLoop.Name & " - " & fldLoop.DataUpdatable
  Next fldLoop

  Debug.Print "  Data"
  ' Enumerate the recordset.
  Do While Not .EOF
     Debug.Print "    " & !FirstName & " " & _
        !LastName
     .MoveNext
  Loop

  .Close



End With


dbsNorthwind.Close


End Sub

This example opens a snapshot-type Recordset and demonstrates its read-only characteristics.

Visual Basic for Applications 
  Sub dbOpenSnapshotX()

Dim dbsNorthwind As Database
Dim rstEmployees As Recordset
Dim prpLoop As Property


Set dbsNorthwind = OpenDatabase("Northwind.mdb")
Set rstEmployees = _
dbsNorthwind.OpenRecordset("Employees", _
dbOpenSnapshot)


With rstEmployees
Debug.Print "Snapshot-type recordset: " & _
.Name


  ' Enumerate the Properties collection of the
  ' snapshot-type Recordset object, trapping for
  ' any properties whose values are invalid in 
  ' this context.
  For Each prpLoop In .Properties
     On Error Resume Next
     Debug.Print "  " & _
        prpLoop.Name & " = " & prpLoop
     On Error Goto 0
  Next prpLoop

  .Close



End With


dbsNorthwind.Close


End Sub

This example opens a table-type Recordset, sets its Index property, and enumerates its records.

Visual Basic for Applications 
  Sub dbOpenTableX()

Dim dbsNorthwind As Database
Dim rstEmployees As Recordset


Set dbsNorthwind = OpenDatabase("Northwind.mdb")
' dbOpenTable is default.
Set rstEmployees = _
dbsNorthwind.OpenRecordset("Employees")


With rstEmployees
Debug.Print "Table-type recordset: " & .Name


  ' Use predefined index.
  .Index = "LastName"
  Debug.Print "  Index = " & .Index

  ' Enumerate records.
  Do While Not .EOF
     Debug.Print "    " & !LastName & ", " & _
        !FirstName
     .MoveNext
  Loop

  .Close



End With


dbsNorthwind.Close


End Sub

See Also