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Three Ways to Open ADO Connection & Recordset Objects

Three Ways to Open ADO Connection & Recordset Objects

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'   1) By Setting the ConnectionString property to a valid Connect string and then calling the Open() method. This connection string is provider- dependent.
'   2) By passing a valid Connect string to the first argument of the Open() method.
'   3) By passing the ODBC Data source name and optionally user-id and password to the Connection Object's Open() method.
' There are three ways to open a Recordset Object within ADO:
'   1) By opening the Recordset off the Connection.Execute() method.
'   2) By opening the Recordset off the Command.Execute() method.
'   3) By opening the Recordset object without a Connection or Command object, and passing an valid Connect string to the second argument of the Recordset.Open() method.
' This code assumes that Nwind.mdb is installed with Visual Basic, and is located in the C:\Program Files\DevStudio\VB directory.
' For more information see Microsoft Knowledgebase Article ID: Q168336 

      Private Sub cmdOpen_Click()

          Dim Conn1 As New adodb.Connection
          Dim Cmd1 As New adodb.Command
          Dim Errs1 As Errors
          Dim Rs1 As New adodb.Recordset
          Dim i As Integer
          Dim AccessConnect As String

          ' Error Handling Variables
          Dim errLoop As Error
          Dim strTmp As String

          AccessConnect = "Driver={Microsoft Access Driver (*.mdb)};" & _
                        "Dbq=nwind.mdb;" & _
                        "DefaultDir=C:\program files\devstudio\vb;" & _
                        "Uid=Admin;Pwd=;"

          '---------------------------

          ' Connection Object Methods

          '---------------------------

          On Error GoTo AdoError  ' Full Error Handling which traverses
                                  ' Connection object

          ' Connection Open method #1:  Open via ConnectionString Property
          Conn1.ConnectionString = AccessConnect
          Conn1.Open
          Conn1.Close
          Conn1.ConnectionString = ""

          ' Connection Open method #2:  Open("[ODBC Connect String]","","")
          Conn1.Open AccessConnect
          Conn1.Close

          ' Connection Open method #3:  Open("DSN","Uid","Pwd")
          Conn1.Open "Driver={Microsoft Access Driver (*.mdb)};" & _
                     "DBQ=nwind.mdb;" & _
                     "DefaultDir=C:\program files\devstudio\vb;" & _
                     "Uid=Admin;Pwd=;"

          Conn1.Close

          '--------------------------

          ' Recordset Object Methods

          '--------------------------

          ' Don't assume that we have a connection object.
          On Error GoTo AdoErrorLite

          ' Recordset Open Method #1:  Open via Connection.Execute(...)
          Conn1.Open AccessConnect
          Set Rs1 = Conn1.Execute("SELECT * FROM Employees")
          Rs1.Close
          Conn1.Close

          ' Recordset Open Method #2:  Open via Command.Execute(...)
          Conn1.ConnectionString = AccessConnect
          Conn1.Open
          Cmd1.ActiveConnection = Conn1
          Cmd1.CommandText = "SELECT * FROM Employees"
          Set Rs1 = Cmd1.Execute
          Rs1.Close
          Conn1.Close
          Conn1.ConnectionString = ""

          ' Recordset Open Method #3:  Open w/o Connection & w/Connect String
          Rs1.Open "SELECT * FROM Employees", AccessConnect, adOpenForwardOnly
          Rs1.Close
Done:

          Set Rs1 = Nothing
          Set Cmd1 = Nothing
          Set Conn1 = Nothing
          Exit Sub
AdoError:
          i = 1
          On Error Resume Next
          ' Enumerate Errors collection and display properties of
          ' each Error object (if Errors Collection is filled out)
          Set Errs1 = Conn1.Errors
          For Each errLoop In Errs1
           With errLoop
              strTmp = strTmp & vbCrLf & "ADO Error # " & i & ":"
              strTmp = strTmp & vbCrLf & "   ADO Error   # " & .Number
              strTmp = strTmp & vbCrLf & "   Description   " & .Description
              strTmp = strTmp & vbCrLf & "   Source        " & .Source
              i = i + 1
           End With
          Next

AdoErrorLite:

          ' Get VB Error Object's information
          strTmp = strTmp & vbCrLf & "VB Error # " & Str(Err.Number)
          strTmp = strTmp & vbCrLf & "   Generated by " & Err.Source
          strTmp = strTmp & vbCrLf & "   Description  " & Err.Description
          MsgBox strTmp
          ' Clean up gracefully without risking infinite loop in error handler
          On Error GoTo 0
          GoTo Done

End Sub