Logging into table in SQL Server trigger

Question

I am coding SQL Server 2005 trigger. I want to make some logging during trigger execution, using INSERT statement into my log table. When there occurs error during execution

Answer 1

Checkout error handling in triggers.

Answer 2

Another possible option is to use a table variable to capture the info you want to store in your permanent log table. Table variables are not rolled back if a ROLLBACK TRANSACTION command is given. Sample code is below...

--- Declare table variable
DECLARE @ErrorTable TABLE
  ( [DATE]  smalldatetime,
    [ENTRY] varchar(64) )

DECLARE @nErrorVar  int

--- Open Transaction
BEGIN TRANSACTION

--- Pretend to cause an error and catch the error code
SET @nErrorVar = 1  --- @@ERROR

IF (@nErrorVar = 1)
  BEGIN

    --- Insert error info table variable
    INSERT INTO @ErrorTable 
      ( [Date], [Entry] )
    SELECT
        getdate(), 'Error Message Goes Here'

    RAISERROR('Error Message Goes Here', 16, 1)

    ROLLBACK TRANSACTION

    --- Change this to actually insert into your permanent log table
    SELECT  *
    FROM    @ErrorTable

  END

IF @@TRANCOUNT  0
  PRINT 'Open Transactions Exist'
ELSE
  PRINT 'No Open Transactions'

Answer 3

Don't know if I'm thinking too simple, but why not just change the order of the error handler to insert AFTER the rollback??

if (@err = 1)
begin
    RAISERROR (@msg, 16, 1)
    rollback transaction
    INSERT INTO dbo.log(date, entry) SELECT getdate(), 'ERROR: ' + out from #output
    return
end

Answer 4

The problem here is that logging is part of transaction that modifies your data. Nested transactions will not help here. What you need is to put you logging actions into a separate context (connection), i.e. make it independent from you current transaction.

Two options come to my mind:

• use Service Broker for logging - put log data to queue, receive and save the data 'on the other side of the pipe' (i.e. in another process/connection/transaction)
• use OPENQUERY - you will need to register you own server as a 'linked server' and execute queries 'remotely' (I know, this looks a little bit strange, but an option anyway ...)

HTH