Oracle SQL, PLSQL, APEX How To's by Dr. S. Raghunathan - HTML preview

17 – HOW TO CREATE TRIGGERs

Trigger means a device or small unit of snatch has been pulled to release fire arm is called Trigger, In Oracle, to initiate an action at some definite point, a code will be written which can be called as Trigger,

Triggers are commonly used to:

• prevent changes ( wrong data entry in table )

• log 1 audit changes ( user identity on last usage time )

• enforce business rules (e,g, less than 18 years aged person cannot give entry for date of Joining since it is prohibited )

• execute business rules (e,g, notify a manager every time an employee's bank account number changes)

• replicate, enhance performance (e,g, on every purchase 1 sale the updating the stock figures on some other table and log maintenance)

The following are maJor features of database triggers and their effects: