Plsql trigger if updating

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Also, if global package variables are updated within a trigger, then it is best to initialize those variables in a , because a cursor must be opened for every execution of a trigger.

Trigger Evaluation Order Although any trigger can run a sequence of operations either in-line or by calling procedures, using multiple triggers of the same type enhances database administration by permitting the modular installation of applications that have triggers on the same tables.

Any view that contains one of those constructs can be made updatable by using an CREATE TABLE Project_tab ( Prj_level NUMBER, Projno NUMBER, Resp_dept NUMBER); CREATE TABLE Emp_tab ( Empno NUMBER NOT NULL, Ename VARCHAR2(10), Job VARCHAR2(9), Mgr NUMBER(4), Hiredate DATE, Sal NUMBER(7,2), Comm NUMBER(7,2), Deptno NUMBER(2) NOT NULL); CREATE TABLE Dept_tab ( Deptno NUMBER(2) NOT NULL, Dname VARCHAR2(14), Loc VARCHAR2(13), Mgr_no NUMBER, Dept_type NUMBER); CREATE OR REPLACE VIEW manager_info AS SELECT e.ename, e.empno, d.dept_type, d.deptno, p.prj_level, p.projno FROM Emp_tab e, Dept_tab d, Project_tab p WHERE e.empno = d.mgr_no AND d.deptno = p.resp_dept; CREATE OR REPLACE TRIGGER manager_info_insert INSTEAD OF INSERT ON manager_info REFERENCING NEW AS n -- new manager information FOR EACH ROW DECLARE rowcnt number; BEGIN SELECT COUNT(*) INTO rowcnt FROM Emp_tab WHERE empno = :n.empno; IF rowcnt = 0 THEN INSERT INTO Emp_tab (empno,ename) VALUES (:n.empno, :n.ename); ELSE UPDATE Emp_tab SET Emp_tab.ename = :n.ename WHERE Emp_tab.empno = :n.empno; END IF; SELECT COUNT(*) INTO rowcnt FROM Dept_tab WHERE deptno = :n.deptno; IF rowcnt = 0 THEN INSERT INTO Dept_tab (deptno, dept_type) VALUES(:n.deptno, :n.dept_type); ELSE UPDATE Dept_tab SET Dept_tab.dept_type = :n.dept_type WHERE Dept_tab.deptno = :n.deptno; END IF; SELECT COUNT(*) INTO rowcnt FROM Project_tab WHERE Project_tab.projno = :n.projno; IF rowcnt = 0 THEN INSERT INTO Project_tab (projno, prj_level) VALUES(:n.projno, :n.prj_level); ELSE UPDATE Project_tab SET Project_tab.prj_level = :n.prj_level WHERE Project_tab.projno = :n.projno; END IF; END; triggers can also be created over nested table view columns. CALL foo (ora_login_user) / CREATE OR REPLACE PROCEDURE Before_delete (Id IN NUMBER, Ename VARCHAR2) IS language Java name 'thjv Triggers.before Delete ( CHAR)'; CREATE OR REPLACE TRIGGER Pre_del_trigger BEFORE DELETE ON Tab FOR EACH ROW CALL Before_delete (:old. Ename) / Within a trigger body of a row trigger, the PL/SQL code and SQL statements have access to the old and new column values of the current row affected by the triggering statement.

These triggers provide a way of updating elements of the nested table. Two correlation names exist for every column of the table being modified: one for the old column value, and one for the new column value.

Triggers can be: Trigger names must be unique with respect to other triggers in the same schema.

A relational database does not guarantee the order of rows processed by a SQL statement.

view is one that lets you perform DML on the underlying table. These statements are run if the triggering statement is entered and if the trigger restriction (if included) evaluates to CONNECT system/manager GRANT ADMINISTER DATABASE TRIGGER TO scott; CONNECT scott/tiger CREATE TABLE audit_table ( seq number, user_at VARCHAR2(10), time_now DATE, term VARCHAR2(10), job VARCHAR2(10), proc VARCHAR2(10), enum NUMBER); CREATE OR REPLACE PROCEDURE foo (c VARCHAR2) AS BEGIN INSERT INTO Audit_table (user_at) VALUES(c); END; CREATE OR REPLACE TRIGGER logontrig AFTER LOGON ON DATABASE -- Just call an existing procedure.

Some views are inherently updatable, but others are not because they were created with one or more of the constructs listed in"Views that Require INSTEAD OF Triggers". The ORA_LOGIN_USER is a function -- that returns information about the event that fired the trigger.

A trigger is a pl/sql block structure which is fired when a DML statements like Insert, Delete, Update is executed on a database table.

A trigger is triggered automatically when an associated DML statement is executed.

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