DBMS3

SET serveroutput ON;

DECLARE
    an ACCNTS.ACCNO%TYPE := &accountnumber;
    op CHAR := &operation;
    amt NUMBER := &amount;
    bal NUMBER;
    less_bal EXCEPTION;

BEGIN
    SELECT BALANCE INTO bal FROM ACCNTS WHERE ACCNO = an;
    IF(op = 'D') THEN
       UPDATE ACCNTS SET BALANCE = BALANCE + amt WHERE ACCNO = an;
       DBMS_OUTPUT.put_line('The amount has been deposited');
    ELSE
        IF(bal < amt) THEN
            RAISE less_bal;
        ELSE
            UPDATE ACCNTS SET BALANCE = BALANCE - amt WHERE ACCNO = an;
        END IF;
    END IF;

    EXCEPTION
        WHEN less_bal THEN
            DBMS_OUTPUT.put_line('Insufficient balance! Transaction could not be completed');
END;