MySQL连接两个单独的查询结果答案

【问题标题】：MySQL join two separate query resultsMySQL连接两个单独的查询结果
【发布时间】：2013-12-29 03:38:50
【问题描述】：

我有两个不同的查询，例如

// This query will return past month records
SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS 'bookingdate', COUNT(*) AS bookings
FROM booking b JOIN restaurants r ON r.list_id = b.list_id
WHERE b.bookingdate BETWEEN 1383224400 AND 1385730000 GROUP BY b.list_id

// This query will return current month records
SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS 'bookingdate', COUNT(*) AS bookings
FROM booking b JOIN restaurants r ON r.list_id = b.list_id
WHERE b.bookingdate BETWEEN 1385816400 AND 1388408400 GROUP BY b.list_id

两个查询的结果字段 list_id、姓名、城市、预订日期、预订

我想将两个查询结果合二为一，并希望结果字段如 list_id、姓名、城市、bookingdate、bookings_lastmonth、bookings_currentmonth

最好的方法是什么？

【问题讨论】：

JOIN 在 SQL 中具有特殊含义，在标题中使用它会让人感到困惑。

标签： mysql

【解决方案1】：

使用UNION属性：-

SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS 'bookingpreviousdate', '0' AS bookingnextdate, COUNT(*) AS bookings
FROM booking b JOIN restaurants r ON r.list_id = b.list_id
WHERE b.bookingdate BETWEEN 1383224400 AND 1385730000 GROUP BY b.list_id
UNION
SELECT b.list_id, r.name, r.city, '0' AS 'bookingpreviousdate', 'FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s')' AS bookingnextdate, COUNT(*) AS bookings
FROM booking b JOIN restaurants r ON r.list_id = b.list_id
WHERE b.bookingdate BETWEEN 1385816400 AND 1388408400 GROUP BY b.list_id

【讨论】：

我想将两个查询结果合二为一，并希望结果字段如 list_id、name、city、bookingdate、bookings_lastmonth、bookings_currentmonth UNION 将给出 list_id、name、city、bookingdate、bookings 等相同字段的结果简而言之，我想要两个不同列中的结果字段“bookings”bookings_lastmonth、bookings_currentmonth
然后再添加一列日期。
'previousmonthdates' 的值不等于 0，'nextmonthdates' 的值不等于 0。

【解决方案2】：

使用union 运算符，它将两个查询放在一张表中

http://dev.mysql.com/doc/refman/5.0/en/union.html

【讨论】：

【解决方案3】：

我不确定预订日期

SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS bookingdate, 
  COUNT(b.list_id) AS bookings_lastmonth, COUNT(c.list_id) AS bookings_currentmonth
FROM restaurants r 
LEFT JOIN booking b ON r.list_id = b.list_id AND b.bookingdate BETWEEN 1383224400 AND 1385730000 
LEFT JOIN booking c ON r.list_id = c.list_id AND c.bookingdate BETWEEN 1385816400 AND 1388408400
GROUP BY r.list_id
HAVING bookings_lastmonth>0 OR bookings_currentmonth>0

【讨论】：

【解决方案4】：

不知何故，它通过这个查询工作

SELECT t1.list_id, t1.name, t1.city, t1.bookings AS bookings_lastmonth, t2.bookings AS bookings_currentmonth 
FROM   (SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS 'bookingdate', COUNT(*) AS bookings 
        FROM   booking b JOIN restaurants r ON r.list_id = b.list_id 
        WHERE  b.bookingdate BETWEEN 1383224400 AND 1385730000 
        GROUP  BY b.list_id) AS t1

        JOIN (SELECT b.list_id, r.name, r.city, FROM_UNIXTIME(b.bookingdate, '%Y-%m-%d- %h:%i:%s') AS 'bookingdate', COUNT(*) AS bookings 
        FROM   booking b JOIN restaurants r 
        ON r.list_id = b.list_id 
        WHERE  b.bookingdate BETWEEN 1385816400 AND 1388408400 
        GROUP  BY b.list_id) AS t2 

        ON t1.list_id = t2.list_id

但我仍然需要为更多改进而努力

【讨论】：