I didn't get the meaning that your SYSPARA table contain only one record.
ok what i got from your code and from your explanation I am sending you the code, please check it...
If your problem is, you want to update each BRANCH_CODE of DPMASTER by newly inserted BRANCH_CODE of SYSPARA table then chnage your Trigger code with the following...
CREATE OR REPLACE TRIGGER INSERT_BRANCH_CODE
AFTER INSERT on DPMASTER
FOR EACH ROW
DECLARE
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
UPDATE DPMASTER SET BRANCH_CODE = (SELECT BRANCH_CODE FROM SYSPARA) WHERE AC_NO = (SELECT :NEW.AC_NO FROM DPMASTER);
COMMIT;
END;
you don't need to mention so much condition because :NEW.AC_NO will return only one record which is newly inserted.
Revert me back if your problem is not solved and tell me the excat error that you are facing.