HOWTO: Retrieve Values in SQL Server Stored Procedures w/ ADO

• Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0

SUMMARY

There are important issues to consider when attempting to retrieve RAISERROR/PRINT/RETURN values from SQL Server stored procedures through ActiveX Data Objects (ADO). Here are three issues:

• RAISERROR statements in SQL Server must be a severity level of 11-18.



• PRINT statements in SQL Server can also populate the ADO errors collection. However, PRINT statements are severity level zero (0) so, at least one RAISERROR statement is required in the stored procedure to retrieve a PRINT statement with ADO through the Errors collection.



• RETURN values in a stored procedure must be associated with at least one resultset.

MORE INFORMATION

The following code sample demonstrates browsing the ADO Errors collection to access the RAISERROR/PRINT/RETURN detail from a SQL Server stored procedure returning multiple resultsets:

1. Paste and execute the following code in the ISQL_W window to create the stored procedure used for the ADO sample in step 4:

   
         use pubs
         GO
   
         if exists (select * from sysobjects where id =
           object_id('dbo.ADOTestRPE') and sysstat & 0xf = 4)
         drop procedure dbo.ADOTestRPE
         GO
   
         create procedure ADOTestRPE
         (
         @SetRtn  INT=0 OUTPUT,
         @R1Num   INT=1,
         @P1Num   INT=1,
         @E1Num   INT=1,
         @R2Num   INT=2,
         @P2Num   INT=2,
         @E2Num   INT=2
         )
         AS
         DECLARE @iLoop     INT
         DECLARE @PrintText VARCHAR(255)
         DECLARE @iErrNum   INT
   
         /*   Check for no Resultsets - needed to get the RETURN value back */ 
         IF @R1Num + @R2Num = 0 SELECT NULL
   
         /*   Resultset 1  ******************************* */ 
   
         IF @R1Num > 0
         BEGIN
            SET ROWCOUNT @R1Num
            SELECT 'Resultset 1' RsNum, Title
            FROM Pubs..Titles
            SET ROWCOUNT 0
         END
   
            /* Must raise a default error context in which to return the PRINT */ 
           /*  statement */ 
          /* (if none present) since PRINT statements are a severity level of */ 
         /*0. */ 
         IF (@P1Num > 0) AND (@E1Num = 0) RAISERROR ("RAISERROR.PError1",
            11, 2)
   
         IF @P1Num > 0
         BEGIN
            SELECT @iLoop = 0
            WHILE @iLoop < @P1Num
            BEGIN
               SELECT @iLoop = @iLoop + 1
               SELECT @PrintText = 'PRINT.Resultset.1: Line ' +
         CONVERT(char(2), @iLoop)
            PRINT @PrintText
           END
         END
   
         IF @E1Num > 0
         BEGIN
            SELECT @iLoop = 0
            WHILE @iLoop < @E1Num
            BEGIN
               SELECT @iLoop = @iLoop + 1
               SELECT @iErrNum = @iLoop + 201000
               RAISERROR ("RAISERROR.Resultset.1", 11, 2)
            END
         END
   
         /*   Resultset 2  ******************************* */ 
   
         IF @R2Num > 0
         BEGIN
            SET ROWCOUNT @R2Num
            SELECT 'Resultset 2' RsNum, Title
            FROM Pubs..Titles
            SET ROWCOUNT 0
         END
   
         /* Must raise a default error context in which to return the PRINT */ 
         /*  statement */ 
         /* (if none present) since PRINT statements are a severity level of */ 
         /*  0. */ 
         IF (@P2Num > 0) AND (@E2Num = 0) RAISERROR ("RAISERROR.PError2",
         11, 2)
   
         IF @P2Num > 0
         BEGIN
            SELECT @iLoop = 0
            WHILE @iLoop < @P2Num
            BEGIN
               SELECT @iLoop = @iLoop + 1
               SELECT @PrintText = 'PRINT.Resultset.2: Line ' +
          CONVERT(char(2), @iLoop)
               PRINT @PrintText
            END
         END
   
         IF @E2Num > 0
         BEGIN
            SELECT @iLoop = 0
            WHILE @iLoop < @E2Num
            BEGIN
               SELECT @iLoop = @iLoop + 1
   
               SELECT @iErrNum = @iLoop + 202000
               RAISERROR ("RAISERROR.Resultset.2", 11, 2)
            END
         END
   
         /*   Return & Output ************************************ */ 
         
         select @SetRtn = -1
         RETURN @SetRtn
         GO
    




2. Create a Standard .EXE project in Visual Basic. Form1 is created by default.



3. From the Project menu, choose References and select the Microsoft ActiveX Data Objects 2.0 Library.
   
   NOTE: You must use ADO 2.0 for the code to work correctly. You can obtain the latest Microsoft Data Access Components (MDAC) components on the Web at the following URL:
   
   http://www.microsoft.com/data/



4. Place a Command button on the Form, and then paste the following code in the General Declarations section of the Form:
   
   NOTE: You may need to change the database connect string for your environment.

   
         'This Code demonstrates RAISERROR/PRINT/RETURN values with ADO and
         'multiple resultsets.
   
         Sub CreateParms()
   
         Dim ADOCmd As New ADODB.Command
         Dim ADOPrm As New ADODB.Parameter
         Dim ADOCon As ADODB.Connection
         Dim ADORs As ADODB.Recordset
         Dim sParmName As String
         Dim strConnect As String
         Dim rStr As String
   
         On Error GoTo ErrHandler
   
         strConnect = "driver={SQL
           Server};server=(local);uid=sa;pwd=;database=pubs"
   
         Set ADOCon = New ADODB.Connection
         With ADOCon
             .Provider = "MSDASQL"
             .CursorLocation = adUseServer  'Must use Server side cursor.
             .ConnectionString = strConnect
             .Open
         End With
   
         Set ADOCmd.ActiveConnection = ADOCon
         With ADOCmd
             .CommandType = adCmdStoredProc
             .CommandText = "ADOTestRPE"
         End With
   
         'Parameter 0 is the stored procedure Return code.
         sParmName = "Return"
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamReturnValue, , 0)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = -1
   
         'Parameter 1 is the setting for the stored procedure Output
         ' parameter.
         sParmName = "Output"
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamOutput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 999
   
         'Parameter 2
         sParmName = "R1Num"     'Number of rows to return in Resultset 1.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 1
   
         'Parameter 3
         sParmName = "P1Num"     'Number of PRINT statements in Resultset 1.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
          adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 0
   
         'Parameter 4
         sParmName = "E1Num"     'Number of RAISERROR statements in Resultset
                                 '1.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 0
   
         'Parameter 5
         sParmName = "R2Num"     'Number of rows to return in Resultset 2.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 2
   
         'Parameter 6
         sParmName = "P2Num"     'Number of PRINT statements in Resultset 2.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
           adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 0
   
         'Parameter 7
         sParmName = "E2Num"     'Number of RAISERROR statements in Resultset
                                 ' 2.
         Set ADOPrm = ADOCmd.CreateParameter(sParmName, adInteger, _
          adParamInput)
         ADOCmd.Parameters.Append ADOPrm
         ADOCmd.Parameters(sParmName).Value = 0
   
         Set ADORs = ADOCmd.Execute
   
         Do While (Not ADORs Is Nothing)
             If ADORs.State = adStateClosed Then Exit Do
             While Not ADORs.EOF
                 For i = 0 To ADORs.Fields.Count - 1
                     rStr = rStr & " : " & ADORs(i)
                 Next i
                 Debug.Print Mid(rStr, 3, Len(rStr))
                 ADORs.MoveNext
                 rStr = ""
             Wend
             Debug.Print "----------------------"
             Set ADORs = ADORs.NextRecordset
         Loop
   
         Debug.Print "Return: " & ADOCmd.Parameters("Return").Value
         Debug.Print "Output: " & ADOCmd.Parameters("Output").Value
   
         GoTo Shutdown
   
         ErrHandler:
             Call ErrHandler(ADOCon)
             Resume Next
   
         Shutdown:
             Set ADOCmd = Nothing
             Set ADOPrm = Nothing
             Set ADORs = Nothing
             Set ADOCon = Nothing
   
         End Sub
   
         Private Sub Command1_Click()
   
         Call CreateParms
   
         End Sub
   
         Sub ErrHandler(objCon As Object)
   
         Dim ADOErr As ADODB.Error
         Dim strError As String
   
         For Each ADOErr In objCon.Errors
          strError = "Error #" & ADOErr.Number & vbCrLf & ADOErr.Description _
             & vbCr & _
              "   (Source: " & ADOErr.Source & ")" & vbCr & _
              "   (SQL State: " & ADOErr.SQLState & ")" & vbCr & _
              "   (NativeError: " & ADOErr.NativeError & ")" & vbCr
          If ADOErr.HelpFile = "" Then
              strError = strError & "   No Help file available" & vbCr & vbCr
          Else
              strError = strError & "   (HelpFile: " & ADOErr.HelpFile & ")" _
          & vbCr & _
                          "   (HelpContext: " & ADOErr.HelpContext & ")" & _
          vbCr & vbCr
          End If
          Debug.Print strError
         Next
   
         objCon.Errors.Clear
   
         End Sub 




5. Change the value of parameters two through seven to alter the number of PRINT statements and/or RAISERROR statements generated by the stored procedure and returned through ADO. Run the Visual Basic code sample again and note that the RAISERROR and PRINT statements are returned through the ADO errors collection. Change the values to experiment with different combinations of PRINT/RAISERROR statements with different resultsets. Please refer to the SQL stored procedures for specific workarounds for special cases.
   
   NOTE: To retrieve a RETURN value in ADO with a stored procedure there must be at least one resultset. In order to work around this problem, when no resultsets are specified (in the ADO sample code) the stored procedure executes a SELECT NULL to return a null resultset to ADO thereby populating the RETURN value. In addition, to work around the issue of specifying no RAISERROR statements and a combination of PRINT statements, default RAISERROR statements are generated in order to provide a context for returning the PRINT statement via ADO. You must code RAISERROR statements in the format shown in the stored procedure because only severity levels of 11-18 return through the ADO errors collection.

REFERENCES

Transact-SQL Help: search on: "PRINT/RAISERROR statement"

For more information, please see the following article in the Microsoft Knowledge Base:

Q190988 HOWTO: Open ADO Recordsets Asynchronously Using WithEvents

Additional query words:

Keywords          : kbprint kbADO200 kbVBp kbVBp500 kbVBp600 
Version           : WINDOWS:5.0,6.0
Platform          : WINDOWS 
Issue type        : kbhowto 

Last Reviewed: July 2, 1999