Error handling not available with linked servers

Question

Hello,
I have a stored procedure which inserts data to a linked mysql Server. The table in mysql has a unique key and I try to insert a new record with a conflicting key.
My problem is that I am not able to do an error handling because my script stops immediatly when the error in the SP occurs.
The error message itself is ok. But why is the script cancelled? So I don't have a possibility to do some error handling. I am working against SQL Server 2000. No TRY CATCH is available.
Here is my code:
DECLARE @RC int
DECLARE @ItemNr nvarchar(255)
DECLARE @Hostname nvarchar(255)
DECLARE @IpAdresse nvarchar(255)
DECLARE @LogLevel int
DECLARE @Message nvarchar(1000)
DECLARE @LocalError int
-- Error handling is working as expected
PRINT 1/0
SELECT @LocalError=@@ERROR
IF @LocalError<>0
 PRINT 'Error'
ELSE
 PRINT 'Success'
SELECT @ItemNr='AN12326m', @Hostname='hostname' ,@IpAdresse='ipadresse', @LogLevel=99, @Message='Test', @RC=0
-- Error handling does not work
EXECUTE [Asset].[dbo].[p_kapaya_DbSync_InsertMySqlRecord]
   @AssetNr, @Hostname, @IpAdresse, @LogLevel, @Message OUTPUT, @RC OUTPUT
-- The following code is not reached, when an error occurs because the execution of the script is cancelled
SELECT @LocalError=@@ERROR
IF @LocalError <>0
 PRINT @LocalError
ELSE
 PRINT 'Success'
Error Message
Der OLE DB-Anbieter 'MSDASQL' für den Verbindungsserver 'MySQL' hat die Meldung '[MySQL][ODBC 5.1 Driver][mysqld-5.0.67-community-nt]Duplicate entry 'AN12326m' for key 1' zurückgeben.
Meldung 7343, Ebene 16, Status 2, Prozedur p_kapaya_DbSync_InsertMySQLRecord, Zeile 57
Der OLE DB-Anbieter 'MSDASQL' für den Verbindungsserver 'MySQL' konnte INSERT INTO für die [MSDASQL]-Tabelle nicht ausführen.
Kind regards
Patrick

Answer 1

This is not unique to linked servers. When an error occurs, there are several actions that SQL Server can take. It can abort the batch, it can abort the current scope or it can just termintate the current statement. Any active transaction may or may not
be rolled back. And this is not all.
Which of these actions, SQL Server takes it is hard to predict, becuase the developers have to have rolled a dice on deciding which action to take. Although, if you have SET XACT_ABORT ON, it is more consistent: in this case, most errors aborts the batch
and rolls back the transaction.
To trap the error, you need to use TRY-CATCH which permits you to trap most (not all) errors. See here for a quick introduction:
http://www.sommarskog.se/error_handling_2005.html
Erland Sommarskog, SQL Server MVP, [email protected]