Each successive time the trigger is called as a result of the same update statement, the nesting level will increment by 1. The SQL Server configuration option "nested triggers" determines whether an action performed in a trigger can cause the trigger to fire again.
The default value for "nested triggers" is 1, which allows the behavior we saw in our sample.
You could change "nested triggers" to zero and disable trigger nesting.
Oracle Database automatically executes a trigger when specified conditions occur.
The deleted table contains the rows that were updated with their values before the update; the inserted table contains the rows that were updated with their new values.