Triggers are stored programs, which are automatically executed or fired when some event occurs.
This article represents the bare minimum you should understand about triggers before you consider writing one.
2) Statement level trigger - An event is triggered for each sql statement executed.
In Oracle, a sequence object (created by CREATE SEQUENCE statement) is used to generate IDs (auto-increment, identity values).
1) Create the 'product' table and 'product_price_history' table Once the above update query is executed, the trigger fires and updates the 'product_price_history' table.
4)If you ROLLBACK the transaction before committing to the database, the data inserted to the table is also rolled back.
This approach can be thought of as auditing changes to a table.