PROCEDURE update_custom_warranty(p_item IN VARCHAR2, p_days IN NUMBER) IS
    CURSOR c_lock_item IS
        SELECT 'x' 
        FROM item_master 
        WHERE item = p_item 
        FOR UPDATE NOWAIT;
    v_dummy VARCHAR2(1);
BEGIN
    -- 1. Lock the base record
    OPEN c_lock_item;
    FETCH c_lock_item INTO v_dummy;
    
    -- 2. Update the custom extension table safely
    UPDATE item_master_cex
    SET custom_warranty_days = p_days
    WHERE item = p_item;
    
    CLOSE c_lock_item;
EXCEPTION
    WHEN OTHERS THEN
        -- Handle locking exceptions (ORA-00054)
        IF c_lock_item%ISOPEN THEN
            CLOSE c_lock_item;
        END IF;
        RAISE;
END;

FUNCTION validate_dept(p_dept IN NUMBER) RETURN BOOLEAN IS
    v_exists NUMBER;
BEGIN
    SELECT 1 INTO v_exists
    FROM deps
    WHERE dept = p_dept;
    
    RETURN TRUE;
EXCEPTION
    WHEN NO_DATA_FOUND THEN
        -- "Department %s does not exist." (Assuming error code 1001 is set up)
        rtk_errors.set_error('1001', TO_CHAR(p_dept)); 
        RETURN FALSE;
END;