Explain about Triggers ?

Question

Accepted Answer

Triggers are database objects that automatically execute in response to certain events.

Triggers can be used to enforce business rules, audit data changes, and maintain referential integrity.
They can be defined to execute before or after an event, such as a row being inserted, updated, or deleted.
Triggers can also be nested, meaning one trigger can execute another trigger.
Examples of triggers include automatically updating a timestamp when a row is modified, or preventing a delete operation on a table if it would violate a foreign key constraint.

Accepted Answer

Triggers are PLSQL blocks that gets automatically fired when specific event occurs.

Triggers can be 1)DML triggers- insert,update,delete,instead of

2)Non DML triggers i.e ddl triggers,system triggers

3)compound triggers

1)These are used to secure your data.

2)To avoid wrong inserts of data.

3)To log the table i.e when you want to keep the info about who changed the data or history of changes

4)To enforce some complex integrity rules.

5)Ddl triggers to block dropping of table.

6)System triggers to know who logged on on what time, How much time the session was active like that.

Accepted Answer

Triggers is a stored procedure in database automatically invokes a special event in the database

Accepted Answer

Trigger: Trigger is a name PL/SQL Block that is stored in database and invoked repeatedly. it automatically fires when an event occurs in schema, table or database.

there are two types

1) statement level or table level trigger: if fires only once for each event. if fires once even if no rows are affected by the triggering event.

2) row level trigger: if fires once for each row affected by the triggering event.

Explain about Triggers ?

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