RDBMS PLSQL Program 50 program to generate value of primary key column using MAX function automatically

 CREATE OR REPLACE TRIGGER PKMAX

BEFORE INSERT ON emp

FOR EACH ROW

DECLARE 

    CNT NUMBER;

    veno emp.eno%TYPE;

BEGIN

     SELECT 'E' || LPAD(MAX(TO_NUMBER(SUBSTR(eno,2))),5,'0') INTO veno

     FROM emp;

     :NEW.eno := veno;

EXCEPTION

     WHEN NO_DATA_FOUND THEN

:NEW.eno := 'E00001';

END;

/