MySQL Double Join with Multiple Where Clauses

Question

为什么此查询未考虑“c.max_no_people < = $ max_guests”的Where子句？

SELECT DISTINCT a.id, b.post_id, c.max_no_people 
FROM wp_dopbsp_reservations a 
    INNER JOIN wp_dopbsp_calendars b 
    ON (b.id = a.calendar_id) 
    INNER JOIN wp_dopbsp_settings c 
    ON (b.id = c.calendar_id) 
WHERE (a.check_out >= \"$check_in\" 
      AND a.check_in < \"$check_out\" 
      OR a.check_out <= \"$check_in\" 
      AND a.check_in > \"$check_out\") 
    AND (c.max_no_people <= $max_guests) 
    AND (a.status = 'approved') 

在此先感谢。

Answer 1

试试这个：

SELECT DISTINCT a.id, b.post_id, c.max_no_people 
FROM wp_dopbsp_reservations a 
INNER JOIN wp_dopbsp_calendars b 
ON (b.id = a.calendar_id) 
INNER JOIN wp_dopbsp_settings c 
ON (b.id = c.calendar_id) 
WHERE a.check_out >= \"$check_in\" 
     AND (a.check_in < \"$check_out\" 
     OR a.check_out <= \"$check_in\") 
     AND a.check_in > \"$check_out\" 
AND (c.max_no_people <= $max_guests) 
AND (a.status = 'approved') 

这是因为你给OR语句，而不在状态，其中使用括号。所以它只会考虑OR语句。

Answer 2

嗯，我认为这个问题是在这里

(a.check_out >= \"$check_in\" 
AND a.check_in < \"$check_out\" 
OR a.check_out <= \"$check_in\" 
AND a.check_in > \"$check_out\") 

岂不是：

(
(a.check_out >= \"$check_in\" 
AND a.check_in < \"$check_out\") OR 
(a.check_out <= \"$check_in\" 
AND a.check_in > \"$check_out\") 
) 

也难逃$ max_guests样（INT）$ max_guests