Error in executing a trigger

Question

Hi
I'm studying Oracle on db10g xe. it comes with default db (hr) and also with on line tutorial which is my starting point.
I was studying trigger with example on EMPLOYEES table that is in tutorial and it's like this:
CREATE OR REPLACE TRIGGER "SECURE_EMP"
BEFORE INSERT OR DELETE OR UPDATE ON EMPLOYEES
FOR EACH ROW
BEGIN
IF TO_CHAR('SYSDATE','DY') IN ('SAT','SUN') OR
TO_CHAR('SYSDATE','HH24') NOT BETWEEN '08' AND '18' THEN
IF DELETING THEN RAISE_APPLICATION_ERROR(-20502,'You may delete from EMPLOYEES table'||
'only during business hours.');
ELSIF INSERTING THEN RAISE_APPLICATION_ERROR(-20500,'You may insert into EMPLOYEES table'||
'only during business hours.');
ELSIF UPDATING('SALARY') THEN RAISE_APPLICATION_ERROR(-20503, 'You may update SALARY'||
'only during business hours.');
ELSE RAISE_APPLICATION_ERROR(-20504,'You may work with EMPLOYEES table'||
'during normal business hours only.');
END IF;
END IF;
END;
it's listed as healthy trigger with now error and when i click on trigger name i go to the page the shows all the detail and it's all normal with no error an anything abnormal.
but when i try to test the trigger implementation with DML (delete,update,insert) i get the following error:
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at "SHAWN_DB_ADMIN.SECURE_EMP", line 2
ORA-04088: error during execution of trigger 'SHAWN_DB_ADMIN.SECURE_EMP'
1. delete from employees where department_id=90
I spent 2 hours and went through each line and syntax but couldn't figure why?
Please let me what's wrong.
the both table creation and trigger code are come as build in part of db10g xe but when i run it it won't work.
Please help.
thanks

Answer 1

You should not quote sysdate so it should be like
CREATE OR REPLACE TRIGGER "SECURE_EMP"
BEFORE INSERT OR DELETE OR UPDATE ON EMPLOYEES
FOR EACH ROW
BEGIN
IF upper(substr(to_char(sysdate,'Day'),1,3)) IN ('SAT','SUN') OR
TO_CHAR(SYSDATE,'HH24') NOT BETWEEN '08' AND '18' THEN
IF DELETING THEN RAISE_APPLICATION_ERROR(-20502,'You may delete from EMPLOYEES table'||
'only during business hours.');
ELSIF INSERTING THEN RAISE_APPLICATION_ERROR(-20500,'You may insert into EMPLOYEES table'||
'only during business hours.');
ELSIF UPDATING('SALARY') THEN RAISE_APPLICATION_ERROR(-20503, 'You may update SALARY'||
'only during business hours.');
ELSE RAISE_APPLICATION_ERROR(-20504,'You may work with EMPLOYEES table'||
'during normal business hours only.');
END IF;
END IF;
END;