Trigger with progressive

Question

Hi,
I've this table:
CREATE TABLE MY_TAB (
ID VARCHAR2 (24) NOT NULL,
NAME_ID VARCHAR2 (32) DEFAULT NULL,
PRIMARY KEY (ID ));
I'd like to create one trigger that for each NAME_ID insert into ID column the value "NAME_ID-progressive of 3 digit"
For example:
INSERT INTO MY_TAB ( NAME_ID) VALUES ('999');
ID..............NAME_ID
999-001.........999
INSERT INTO MY_TAB ( NAME_ID) VALUES ('999');
ID..............NAME_ID
999-001.........999
999-002.........999
INSERT INTO MY_TAB ( NAME_ID) VALUES ('88888');
ID..............NAME_ID
999-001.........999
999-002.........999
88888-001.......88888
INSERT INTO MY_TAB ( NAME_ID) VALUES ('88888');
ID..................NAME_ID
999-001.............999
999-002.............999
88888-001...........88888
88888-002...........88888
INSERT INTO MY_TAB ( NAME_ID) VALUES ('999');
ID..................NAME_ID
999-001.............999
999-002.............999
88888-001...........88888
88888-002...........88888
999-003.............999
INSERT INTO MY_TAB ( NAME_ID) VALUES ('999')
ID..................NAME_ID
999-001.............999
999-002.............999
88888-001...........88888
88888-002...........88888
999-003.............999
999-004.............999
The trigger is like this:
CREATE OR REPLACE TRIGGER TRG_MY_TAB
BEFORE INSERT ON MY_TAB
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
WHEN (NEW.ID IS NULL)
BEGIN
SELECT (:NEW.NAME_ID ||('-here progressive'))
INTO :NEW.ID
FROM DUAL;
END;
How can I create this trigger with progressive
Thank in advance!

Answer 1

Create an auxiliary table:
CREATE TABLE progressive
(name_id VARCHAR2(32) NOT NULL PRIMARY KEY
,seq NUMBER NOT NULL
/And then call this function in your trigger:
CREATE OR REPLACE FUNCTION next_progressive (p_name_id IN progressive.name_id%TYPE)
                           RETURN NUMBER IS
  l_seq NUMBER;
BEGIN
  LOOP
    BEGIN
      SELECT seq INTO l_seq
        FROM progressive
        WHERE name_id = p_name_id
        FOR UPDATE;
      UPDATE progressive
        SET seq = seq + 1
        WHERE name_id = p_name_id;
      RETURN l_seq;
    EXCEPTION
      WHEN no_data_found THEN
        BEGIN
          INSERT INTO progressive (name_id, seq)
            VALUES (p_name_id, 2);
          RETURN 1;
        EXCEPTION
          WHEN dup_val_on_index THEN
            null;
        END;
    END;
  END LOOP;
END;
/