6A compound SQL (compiled) statement cannot be specified if the trigger definition includes a REFERENCING OLD TABLE clause or a REFERENCING NEW TABLE clause. A compound SQL (compiled) statement also cannot be specified for a trigger definition in a partitioned database environment. ...
dbms_output.put_line(‘ Difference ‘ || sal_diff); END; / The size of the Trigger should not exceed 32K. Important Points Trigger will work on DML operations, INSERT,DELETE,UPDATE BEFORE/AFTER key words. When trigger has to execute, we need to given in definition FOR EACH ROW => Tri...
then the trigger is executed without evaluating the expression in theWHENclause. Similarly, if a compound trigger definition includes a row-level trigger having aWHENclause, then the trigger is executed if the expression evaluates toTRUE.
注意: DML:data manipulation language 数据操作语句: select update insert delete 需要提交与回滚事务增删改 DDL : data definition language: 数据库定义语句 create ,alter, drop DCL: data control language 数据库控住语句 grant deny revoke 设置更改数据库用户的角色或者权限 3.为什么要使用事务? 是为了保证数...
The CREATE TRIGGER statement returns an error if the trigger's subject table has row level or column level access control activated. Similarly, the CREATE TRIGGER statement fails if the trigger is defined on a view and one or more of the underlying tables in that view definition has row level...
Another common trigger use is to save important original data, in its unchanged state, to maintain an audit trail or ensure that the original data remains accessible in the event of accidental changes. For example, the same HR application may contain a trigger that is executed when an employee...
Synopsis EDB Postgres Advanced Server supports three variations of theALTER TRIGGERcommand. Use the first variation to change the name of a given trigger without changing the trigger definition: ALTERTRIGGER<name>ONRENAMETO<new_name> Use the second...
Codul este inclusă în script DDL (Data Definition Language) creat atunci când utilizațiExpertul de bază de date actualizaresauGenerare. Puteți rula un trigger atunci când apar anumite date evenimente, cum ar fi atunci când o înregi...
UPDATEcustomersSETsalary=salary+500WHEREid=2; When a record is updated in the CUSTOMERS table, the above create trigger,display_salary_changeswill be fired and it will display the following result − Old salary: 1500 New salary: 2000 Salary difference: 500 ...
(DBMS), a trigger is an SQL procedure that is executed when a record is added or deleted. It is used to maintain referential integrity in the database. A trigger may also execute a stored procedure. Triggers and stored procedures are built into DBMSs used in client/server environments. ...