Business Rule in trigger not working

Question

Hi,
I have business rule that no one below 18 years should be employed in this system.
I have created a trigger that alerts me so, but when ever I insert someone either over 10 or below, it fires and deos not insert any record, but if I deleted the trigger, everything works fine.
I should have put a check constraint (s_hire_date - s_dob) < 6570 on the table, but I just thought should be able to do it.
Why please?
stops insertion of under 18 years into employee table
CREATE OR REPLACE TRIGGER Tr_new_employee
BEFORE INSERT ON employee for each row
DECLARE s_hire_date DATE;
s_dob date;
begin
select :NEW.hire_date, :NEW.dob into s_hire_date, s_dob from employee
where empid =:new.empid;
IF (s_hire_date - s_dob) < 6570 then
raise_application_error(-20101,'Person too young');
end if;
end;
Many thanks in advance
cube60

Answer 1

Hello Warren and All,
Thanks for the code, the trigger did compile successfully, but prevents any kind of insertion whether over 18 or younger.
SQL> CREATE OR REPLACE TRIGGER Tr_new_employee
2 BEFORE INSERT ON employee for each row
3 DECLARE s_hire_date DATE;
4 s_dob date;
5 begin
6
7 select :NEW.hire_date, :NEW.dob into s_hire_date, s_dob from employee
8 where empid =:new.empid;
9
10 IF TRUNC(months_between(s_hire_date,s_dob)/12) < 18 then
11 raise_application_error(-20101,'Person too young');
12 end if;
13 end;
14 /
Trigger created.
SQL> COMMIT;
Commit complete.
SQL> --under 18 to time of hire_date
SQL> EXEC NEW_EMPLOYEE('CHARLES','DICKSON','M','29-JAN-1992','PT2','','','','',sysdate,NULL,09890111
,'HSBC','WANDSWORTH','CURRENT','PR3');
BEGIN NEW_EMPLOYEE('CHARLES','DICKSON','M','29-JAN-1992','PT2','','','','',sysdate,NULL,09890111,'HS
ERROR at line 1:
ORA-01403: no data found
ORA-01403: no data found
ORA-06512: at "SYSTEM.TR_NEW_EMPLOYEE", line 5
ORA-04088: error during execution of trigger 'SYSTEM.TR_NEW_EMPLOYEE'
ORA-06512: at "SYSTEM.NEW_EMPLOYEE", line 26
ORA-06512: at line 1
SQL> COMMIT;
Commit complete.
SQL> --over 18
SQL> EXEC NEW_EMPLOYEE('WARREN','TALENTINO','M','29-JAN-1975','HOURLY','','','','','18-FEB-2001',NUL
L,36901212,'BARCLAYS','SYDENHAM','CURRENT','TEMP7');
BEGIN NEW_EMPLOYEE('WARREN','TALENTINO','M','29-JAN-1975','HOURLY','','','','','18-FEB-2001',NULL,36
ERROR at line 1:
ORA-01403: no data found
ORA-01403: no data found
ORA-06512: at "SYSTEM.TR_NEW_EMPLOYEE", line 5
ORA-04088: error during execution of trigger 'SYSTEM.TR_NEW_EMPLOYEE'
ORA-06512: at "SYSTEM.NEW_EMPLOYEE", line 26
ORA-06512: at line 1
I know your logic is fine, something might be wrong with the trigger even though it created succesfully. It is not doing what it is intended to do.
Many thanks
cube60