Database triggers are stored procedures that automatically execute in response to certain events like data modification on a table. There are different types of triggers including row-level, column-level, and statement-level triggers. Triggers enforce business rules, data integrity, and can log or audit database events. They help manage complex workflows and ensure data consistency across tables and databases.

1. DATABASE TRIGGERS

2. WHAT IS DATABASE TRIGGERS ?

3. ANSWER :
• A DATRABASE TRIGGER IS PROCEDURAL CODE THAT IS AUTOMATICALLY EXECUTED IN
RESPONSE TO CERTAIN EVENTS ON A PARTICULAR TABLE OR VIEW IN A DATABASEE.
• THAT ARE THE PROCEDURES THAT IMPLICITLY EXECUTED WHEN AN EVENT OCCURS
AGAINST ASSOCIATED TABLE.
• TRIGGERS EXECUTES WHEN A USER TRIES TO MODIFY DATA BY DML , DDL EVENT.
• THAT TRIGGERS ARE STORED IN THE DATABASE SEPARATELY FROM THEIR ASSOCIATED
TABLES.
• TRIGGERS ARE EVENT-DRIVEN SPECIALIZED PROCEDURES, THEY ARE STORED IN AND
MANAGED BY THE DBMS

4. HOW AMANY TYPES OF TRIGGERS ?
• THE FOUR MAIN TYPES OF TRIGGERS ARE:
1: ROW LEVEL TRIGGER:
THIS GETS EXECUTED BEFORE OR AFTER ANY COLUMN VALUE OF A ROW CHANGES
2: COLUMN LEVEL TRIGGER:
THIS GETS EXECUTED BEFORE OR AFTER THE SPECIFIED COLUMN CHANGES

5. 3: FOR EACH ROW TYPE
THIS TRIGGER GETS EXECUTED ONCE FOR EACH ROW OF THE
RESULT SET AFFECTED BY AN INSERT/UPDATE/DELETE
4: FOR EACH STATEMENT TYPE:
THIS TRIGGER GETS EXECUTED ONLY ONCE FOR THE ENTIRE
RESULT SET, BUT FIRES EACH TIME THE STATEMENT IS
EXECUTED.

6. WHICH EVENTS ? ? ??
• EVENTS ARE DIFFERENT FOR DML & DDL

7. DML (DATA MODULATION LANGUAGE)
TRIGGERS
• DML EVENTS ARE INSERT, UPDATE, OR DELETE STATEMENTS ON A TABLE OR VIEW.
• DML TIGGERS ARE ALSO CALLED STANDARD TRIGGERS.
• DML TRIGGERS ARE FREQUENTLY USED FOR ENFORCING BUSINESS RULES AND DATA INTEGRITY.
• THE CODE FOR CREATING DML TRIGGER IS ON NEXT SLIDE

8. CREATE TRIGGER [ SCHEMA_NAME . ]TRIGGER_NAME
ON { TABLE | VIEW }
[ WITH <DML_TRIGGER_OPTION> [ ,...N ] ]
{ FOR | AFTER | INSTEAD OF }
{ [ INSERT ] [ , ] [ UPDATE ] [ , ] [ DELETE ] }
[ WITH APPEND ]
[ NOT FOR REPLICATION ]
AS { SQL_STATEMENT [ ; ] [ ,...N ] | EXTERNAL NAME <METHOD SPECIFIER [ ; ] > }
<DML_TRIGGER_OPTION> ::=
[ ENCRYPTION ]
[ EXECUTE AS CLAUSE ]
<METHOD_SPECIFIER> ::=
ASSEMBLY_NAME.CLASS_NAME.METHOD_NAME

9. DDL (DATA DEFINATION LANGUAGE)
TRIGGERS
• DDL EVENTS ARE CREATE, ALTER, DROP STATEMENTS. GRANT, DENY, REVOKE, AND UPDATE STATISTICS
STATEMENT ARE DDL TRIGGERS.
• THE CODE FOR CREATING DDL TRIGGER IS ON NEXT SLIDE

10. CREATE TRIGGER TRIGGER_NAME
ON { ALL SERVER | DATABASE }
[ WITH <DDL_TRIGGER_OPTION> [ ,...N ] ]
{ FOR | AFTER } { EVENT_TYPE | EVENT_GROUP } [ ,...N ]
AS { SQL_STATEMENT [ ; ] [ ,...N ] | EXTERNAL NAME < METHOD SPECIFIER > [ ; ]
}
<DDL_TRIGGER_OPTION> ::=
[ ENCRYPTION ]
[ EXECUTE AS CLAUSE ]
TRIGGER ON A LOGON EVENT (LOGON TRIGGER)
CREATE TRIGGER TRIGGER_NAME
ON ALL SERVER

11. WHAT TYPES OF WORK TRIGGERS DO ?

12. ANSWERS :
• A TRIGGER CAN PERMIT DML OPERATIONS AGAINST A TABLE ONLY IF THEY ARE
ISSUED DURING REGULAR BUSINESS HOURS.
• THE TRIGGER FURTHER RESTRICTS DML OPERATIONS TO OCCUR ONLY AT CERTAIN
TIMES DURING WEEKDAYS.
• AUTOMATICALLY GENERATE DERIVED COLUMN VALUES
• PREVENT INVALID TRANSACTIONS
• ENFORCE COMPLEX SECURITY AUTHORIZATIONS

13. (CONTINUES . . . . .)
•ENFORCE COMPLEX BUSINESS RULES
•PROVIDE TRANSPARENT EVENT LOGGING
•PROVIDE SOPHISTICATED AUDITING
•MAINTAIN SYNCHRONOUS TABLE REPLICATES
•GATHER STATISTICS ON TABLE ACCESS

14. THANK YOU . . . . .