Processing Triggers

Question

Hello
I have to create a Trigger that would insert a new Deptno into a table Dept before insert or update on Emp When Deptno is not found!!
The question is:
I can not find a syntax for "not found"
The code should be as follows:
Create or Replace trigger TriggerDept
Before Insert or Update On Emp
For each row
When (I think here I have to insert something like "new.Deptno != found")
Begin
Insert Into Dept(Deptno, Loc) Values(50, 'LA');
Update Emp
Set Sal = Sal*1.015
Where Deptno = 50;
End;
So this "new.Deptno not found" is not correct
What is a right syntax for that? And the right place to use it??
Thank you

Answer 1

Sloger wrote:
department name 50, location 'LA'
So you want ANY non-existing department to have name 50, location 'LA'? Does not make much sense, does it? Anyway:
CREATE OR REPLACE
  TRIGGER EMP_BIR
  BEFORE INSERT
  ON EMP
  FOR EACH ROW
  BEGIN
      MERGE
        INTO dept d1
        USING (SELECT :new.deptno deptno,'50' dname,'LA' location FROM dual) d2
        ON (d1.deptno = d2.deptno)
        WHEN NOT MATCHED THEN INSERT VALUES(d2.deptno,d2.dname,d2.location);
END;
/ For example:
SQL> DROP TABLE EMP1
  2  /
Table dropped.
SQL> DROP TABLE DEPT1
  2  /
Table dropped.
SQL> CREATE TABLE EMP1 AS SELECT * FROM EMP
  2  /
Table created.
SQL> CREATE TABLE DEPT1 AS SELECT * FROM DEPT
  2  /
Table created.
SQL> ALTER TABLE DEPT1
  2    ADD CONSTRAINT DEPT1_PK
  3    PRIMARY KEY(DEPTNO)
  4  /
Table altered.
SQL> ALTER TABLE EMP1
  2    ADD CONSTRAINT EMP1_FK1
  3    FOREIGN KEY(DEPTNO)
  4    REFERENCES DEPT1(DEPTNO)
  5  /
Table altered.
SQL> CREATE OR REPLACE
  2    TRIGGER EMP1_BIR
  3    BEFORE INSERT
  4    ON EMP1
  5    FOR EACH ROW
  6    BEGIN
  7        MERGE
  8          INTO dept1 d1
  9          USING (SELECT :new.deptno deptno,'50' dname,'LA' location FROM dual) d2
10          ON (d1.deptno = d2.deptno)
11          WHEN NOT MATCHED THEN INSERT VALUES(d2.deptno,d2.dname,d2.location);
12  END;
13  /
Trigger created.
SQL> INSERT INTO EMP1(DEPTNO) VALUES(99)
  2  /
1 row created.
SQL> SELECT  *
  2    FROM  DEPT1
  3  /
    DEPTNO DNAME          LOC
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
        99 50             LA
SQL> SELECT  DEPTNO
  2    FROM  EMP1
  3  /
    DEPTNO
        20
        30
        30
        20
        30
        30
        10
        20
        10
        30
        20
    DEPTNO
        30
        20
        10
        99
15 rows selected.
SQL> SY.