在插入之前，同一表上的触发器不会更新列值

Question

Below is the trigger that am using to generate the value of EMP_ID by concatinating EMP_KEY with some text ,let say the EMP_KEY =2000 and TYPE_ID=1 then depending on the condition ,the value of EMP_ID should be CON2000 and so on. But when a record is inserted,the value of EMP_ID is generated just 'CON' and while a record is updated ,its working properly ie EMP_ID=CON2000 .

In this case, EMP_KEY is an autogenerated field and its NOT NULL

What mistake am i making?Can someone please help? I tiried with AFTER and using reference OLD as old and NEW as new,but no luck.

CREATE OR REPLACE TRIGGER EMP_ID_TRIGG BEFORE
INSERT OR UPDATE ON EMP 
FOR EACH ROW 
BEGIN 
IF :NEW.TYPE_ID = 1 THEN :NEW.EMP_ID := CONCAT('CON', :NEW.EMP_KEY);
ELSIF :NEW.TYPE_ID = 2 THEN :NEW.EMP_ID := CONCAT('SUBCON', 
:NEW.EMP_KEY);
ELSIF :NEW.TYPE_ID = 3 THEN :NEW.EMP_ID := CONCAT('JV', :NEW.EMP_KEY);
ELSE :NEW.EMP_ID := :NEW.EMP_KEY;
END IF;
END;

Answer 1

It sounds like you have two triggers on the table, one to generate the key (presumably from a sequence), then the one you have shown to use that key value to generate the ID. Simple demo:

create table emp (emp_key number primary key,
  type_id number,
  emp_id varchar2(20),
  emp_name varchar2(20)
);

create sequence emp_key_seq;

create or replace trigger emp_key_trigg
before insert on emp
for each row 
begin 
  :new.emp_key := emp_key_seq.nextval;
end;
/

create or replace trigger emp_id_trigg
before insert or update on emp 
for each row 
begin 
  if :new.type_id = 1 then
    :new.emp_id := concat('CON', :new.emp_key);
  elsif :new.type_id = 2 then
    :new.emp_id := concat('SUBCON', :new.emp_key);
  elsif :new.type_id = 3 then
    :new.emp_id := concat('JV', :new.emp_key);
  else
    :new.emp_id := :new.emp_key;
  end if;
end;
/

then inserting and updating does what you describe:

insert into emp (type_id, emp_name) values (1, 'Jane');
insert into emp (type_id, emp_name) values (2, 'Joe');

select * from emp;

   EMP_KEY    TYPE_ID EMP_ID               EMP_NAME            
---------- ---------- -------------------- --------------------
         1          1 CON                  Jane                
         2          2 SUBCON               Joe                 

update emp set emp_name = 'Jen' where emp_name = 'Jane';

select * from emp;

   EMP_KEY    TYPE_ID EMP_ID               EMP_NAME            
---------- ---------- -------------------- --------------------
         1          1 CON1                 Jen                 
         2          2 SUBCON               Joe                 

From 11g you can control the order that triggers with the same timing point fire with the FOLLOWS clause , so in this case ad follow emp_key_trigg (with the name of your actual trigger, of course):

create or replace trigger emp_id_trigg
before insert or update on emp 
for each row
follows emp_key_trigg
begin 
  if :new.type_id = 1 then
    :new.emp_id := concat('CON', :new.emp_key);
  elsif :new.type_id = 2 then
    :new.emp_id := concat('SUBCON', :new.emp_key);
  elsif :new.type_id = 3 then
    :new.emp_id := concat('JV', :new.emp_key);
  else
    :new.emp_id := :new.emp_key;
  end if;
end;
/

insert into emp (type_id, emp_name) values (1, 'Jane');
insert into emp (type_id, emp_name) values (2, 'Joe');

select * from emp;

   EMP_KEY    TYPE_ID EMP_ID               EMP_NAME            
---------- ---------- -------------------- --------------------
         3          1 CON3                 Jane                
         4          2 SUBCON4              Joe                 

---

You could also combine the two triggers into one (which you'd have to do on earlier releases anyway, as triggers of the same type for the same statement are not guaranteed to fire in any specific order ):

-- don't do this unless you're sure it's what you have to do!
drop trigger emp_key_trigg;

create or replace trigger emp_id_trigg
before insert or update on emp 
for each row 
begin 
  if inserting then
    :new.emp_key := emp_key_seq.nextval;
  end if;

  if :new.type_id = 1 then
    :new.emp_id := concat('CON', :new.emp_key);
  elsif :new.type_id = 2 then
    :new.emp_id := concat('SUBCON', :new.emp_key);
  elsif :new.type_id = 3 then
    :new.emp_id := concat('JV', :new.emp_key);
  else
    :new.emp_id := :new.emp_key;
  end if;
end;
/

insert into emp (type_id, emp_name) values (1, 'Jane');
insert into emp (type_id, emp_name) values (2, 'Joe');

select * from emp;

   EMP_KEY    TYPE_ID EMP_ID               EMP_NAME            
---------- ---------- -------------------- --------------------
         5          1 CON5                 Jane                
         6          2 SUBCON6              Joe                 

Answer 2

Works OK for me on 11gR2:

SQL> CREATE TABLE test
  2  (
  3     type_id   NUMBER,
  4     emp_id    VARCHAR2 (20),
  5     emp_key   VARCHAR2 (20)
  6  );

Table created.

SQL> CREATE OR REPLACE TRIGGER EMP_ID_TRIGG
  2     BEFORE INSERT OR UPDATE
  3     ON test
  4     FOR EACH ROW
  5  BEGIN
  6     IF :NEW.TYPE_ID = 1
  7     THEN
  8        :NEW.EMP_ID := CONCAT ('CON', :NEW.EMP_KEY);
  9     ELSIF :NEW.TYPE_ID = 2
 10     THEN
 11        :NEW.EMP_ID := CONCAT ('SUBCON', :NEW.EMP_KEY);
 12     ELSIF :NEW.TYPE_ID = 3
 13     THEN
 14        :NEW.EMP_ID := CONCAT ('JV', :NEW.EMP_KEY);
 15     ELSE
 16        :NEW.EMP_ID := :NEW.EMP_KEY;
 17     END IF;
 18  END;
 19  /

Trigger created.

SQL>

Testing:

SQL> INSERT INTO test (type_id, emp_key) VALUES (1, 'X');

1 row created.

SQL> SELECT * FROM test;

   TYPE_ID EMP_ID               EMP_KEY
---------- -------------------- --------------------
         1 CONX                 X

SQL> UPDATE test SET type_id = 2;

1 row updated.

SQL> SELECT * FROM test;

   TYPE_ID EMP_ID               EMP_KEY
---------- -------------------- --------------------
         2 SUBCONX              X

SQL>

Are you sure EMP_KEY is not NULL while inserting? That might cause what you're saying.

Otherwise, do edit your question and copy/paste SQL*Plus session so that we could see what you did and how Oracle responded.