The code generated by the three stored procedures call another stored procedure ErrorHandler.
The reason that I did not include the ErrorHandler as a stored procedure is that this procedure 
is customized for every project. ErrorHandler is supposed to translate the error into a human 
readable message. Below is a very simplistic ErrorHandler:

CREATE PROCEDURE ErrorHandler
	@error_number integer,
	@table_name sysname,
	@action sysname
AS
	declare @message varchar ( 100 ),
		@error_string varchar ( 10 ),
		@error_message varchar ( 255 )

	select @message = 'Error %s record in %s. '
	if @action = 'adding' or @action = 'updating'
	begin
		if @error_number = 2627
			select @message = @message + 'Duplicate code entered.'
		if @error_number = 547
			select @message = @message + 'Constraint error. Please check the data entered.'
		if @error_number = 532
			select @message = @message + 'Data has been changed by another user.'
	end

	if @action = 'deleting'
	begin
		if @error_number = 547
			select @message = @message + 'Code is being referenced by another table.'
	end
	
	exec master..xp_sprintf @error_message output, @message, @action, @table_name
	raiserror ( @error_message, 18, 1 )
go

This should show you how to write your own ErrorHandler procedure. You can even send your own 
error number and set a proper error message here.

Ideally, there should be a procedure at the front-end which will parse the error messages from 
the back-end and show a proper message. Below is a quick and dirty VB function sample for RDO 
(I hope this works). Please don't comment on the use of GOSUB (old habits die hard <g>).

Public Function DecodeSQLErrorMessage() As String
    Const source$ = "[SQL Server]"
    
    Dim i%
    Dim msg$, strMsg$
    Dim rderr As rdoError
    Dim ary1 As Variant, ary2 As Variant
    Dim intStartPos%, intStopPos%
    
    For i = 0 To rdoErrors.Count - 1
        Set rderr = rdoErrors(i)
        If InStr(rderr.Description, source) <> 0 Then
            GoSub DECODE_ERROR
        End If
    Next
    
    If strMsg = "" Then
        For i = 0 To rdoErrors.Count - 1
            Set rderr = rdoErrors(i)
            strMsg = strMsg & vbCrLf & rderr.Description
        Next
    End If
    
    DecodeSQLErrorMessage = strMsg
    Exit Function
    
    
DECODE_ERROR:
    
    msg$ = rderr.Description
    intStartPos = InStr(msg, source) + Len(source)
    Select Case rderr.Number
        Case 547
            ary1 = Array(" statement conflicted with ", " constraint '", _
                        "'. The conflict occurred in database '", "', table '", "', ", " '", "'")
            ary2 = Array("Statement :  ", "Error Type :  ", "Constraint :  ", "Database :  ", "Table :  ", "Object Type :  ", "Object Name :  ")
            For i = LBound(ary1) To UBound(ary1)
                intStopPos = InStr(intStartPos + 1, msg$, ary1(i))
                If intStopPos <> 0 Then
                    strMsg = strMsg & vbCr & ary2(i) & Mid$(msg$, intStartPos, intStopPos - intStartPos)
                    intStartPos = intStopPos + Len(ary1(i))
                End If
            Next
            Erase ary1
            Erase ary2
            
        Case 2627
            ary1 = Array(" constraint '", _
                        "': Attempt to insert duplicate key in object '", "'.")
            ary2 = Array("Error Type :  ", "Constraint :  ", "Table :  ")
            For i = LBound(ary1) To UBound(ary1)
                intStopPos = InStr(intStartPos + 1, msg$, ary1(i))
                If intStopPos <> 0 Then
                    strMsg = strMsg & vbCr & ary2(i) & Mid$(msg$, intStartPos, intStopPos - intStartPos)
                    intStartPos = intStopPos + Len(ary1(i))
                End If
            Next
            Erase ary1
            Erase ary2
        
        Case Else
            strMsg = strMsg & vbCr & Mid(msg, intStartPos) & vbCr
            
    End Select
    
    Return

End Function



Hope this info helped. Maybe some one can spend time on building this further using by using 
pattern matching and also build something for ADO. Any corrections, suggestions and comments 
are welcome as I havn't had the time to test the stuff.

:-)

Hemant Sahgal
hemant@irissoftware.com