Database Triggers: Database Triggers are Procedures that are automatically executed as a result of insert in, update to, or delete from table.
Database triggers have the values old and new to denote the old value in the table before it is deleted and the new indicated the new value that will be used. Database Triggers are useful for implementing complex business rules, which cannot be enforced using the integrity rules. We can have the trigger as before trigger or After Trigger and at Statement or Row level.
E.g.: operations insert, update, and delete 3
Before, after 3*2 A total of 6 combinations
At statement level (once for the trigger) or row level (for every execution) 6 * 2 A
total of 12.
Thus a total of 12 combinations are there and the restriction of usage of 12 triggers has been lifted from Oracle 7.3 Onwards.