SQL查询不显示结果

Question

我正在写一个SQL查询，这是我到目前为止所做的。但是，尽管它们存在于数据库中，但它不会显示结果。我看了一下，我只是没有看到它可能出现的问题。一个偶然的机会，有人看到这里可能会出现什么问题吗？

SELECT customer_Name AS "Customer Name", 
       customer_Telephone AS "Customer Tel.", 
       rent_date AS "Date Out", 
       date_due AS "Date Due", 
       (bike_Number +' ' + bike_Model) AS "Bike No. and Model"
FROM rental_record
  JOIN Customer using (customer_ID)
  JOIN bike_Record using (bike_Number)
WHERE sysdate > date_Due 
  AND time_Actual = NULL
ORDER BY date_due DESC;

Answer 1

改变这个：

  AND time_Actual = NULL

对此：

  AND time_Actual IS NULL