如何在oracle 6i中验证特定的用户密码？

CREATE OR REPLACE PROCEDURE validate_password (
    p_username IN VARCHAR2,
    p_password IN VARCHAR2,
    p_valid OUT VARCHAR2
) AS
    v_count NUMBER;
BEGIN
    SELECT COUNT(*)
    INTO v_count
    FROM users
    WHERE username = p_username
    AND password = p_password;

    IF v_count > 0 THEN
        p_valid := 'Valid';
    ELSE
        p_valid := 'Invalid';
    END IF;
END;

DECLARE
    v_valid VARCHAR2(10);
BEGIN
    validate_password('john', 'password123', v_valid);
    DBMS_OUTPUT.PUT_LINE('Password validation result: ' || v_valid);
END;