Microsoft SQL Server 2014 Unleashed

Triggers and Transaction Nesting

To demonstrate the relationship between a trigger and the transaction nesting level, you can use the following SQL code to create a trigger on the employee table:

Click here to view code image

use AdventureWorks2012goCREATE TRIGGER tD_auditlog ON employeeFOR DELETEAS   DECLARE @msg VARCHAR(255)   SELECT @msg = 'Trancount in trigger = ' + CONVERT(VARCHAR(2), @@trancount)   PRINT @msg   RETURNgo

The purpose of this trigger is simply to show the state of the @@trancount within the trigger as the deletion is taking place.

If you now execute code for implied and explicit transactions, you can see the values of @@trancount and behavior of the batch. First, here’s the implied transaction:

Click here to view code image ...