SQL查询负号运算

Question

SELECT flight_id, depart, arr, price 
FROM user.flightdb t2 LEFT JOIN 
    user.booking t1 
    ON t1.flightID = t2.flight_id 
WHERE t2.source = 1 and t2.dest = 4 and 
     t1.date = "02/02/2016" and t1.flightID IS NULL; 

我想从flightdb（表）中选择那些flight_id，他们应该具有源和目的地，并且在特定日期没有出现在预订（表格）中。

所以这将是在MySQL

Answer 1

您可以使用left join的查询，但在第二个表的条件需要是on子句。此外，你应该使用合适的日期格式：

SELECT flight_id, depart, arr, price 
FROM user.flightdb t2 LEFT JOIN 
    user.booking t1 
    ON t1.flightID = t2.flight_id and t1.date = '2016-02-02' 
WHERE t2.source = 1 and t2.dest = 4 and t1.flightID IS NULL; 

Answer 2

你可以使用下面的查询

SELECT flight_id, depart, arr, price 
     FROM user.flightdb t2 LEFT JOIN 
     user.booking t1 ON t1.flightID = t2.flight_id 
    and t2.source = 1 and t2.dest = 4 AND 
     t1.date = "02/02/2016" WHERE t1.flightID IS NULL;