Oracle triggers when updating
1) Row level trigger - An event is triggered for each row upated, inserted or deleted.
2) Statement level trigger - An event is triggered for each sql statement executed.
It is very important to include the INNER JOIN to the INSERTED table so that only the updated rows are affected.
4)If you ROLLBACK the transaction before committing to the database, the data inserted to the table is also rolled back.
There are two types of triggers based on the which level it is triggered.
A trigger is a pl/sql block structure which is fired when a DML statements like Insert, Delete, Update is executed on a database table.
A trigger is triggered automatically when an associated DML statement is executed.