mysql - SELECT 语句具有不同的列数

Question

我试过使用下面的代码，上面写着

The used SELECT statements have a different number of columns

因为添加的距离列在第二个查询中更多。我该如何解决这样的问题，或者我能否在没有距离列的情况下获得正确的顺序？我非常感谢任何帮助。提前致谢。

SELECT * FROM
(
   SELECT * FROM user u
   INNER JOIN employee e ON (u.empid = e.empid)
   INNER JOIN awards a ON (u.empid = a.empid)
   WHERE u.empid = 123

   UNION

   SELECT * ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) )+ sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance
   FROM user u
   INNER JOIN employee e ON (u.empid = e.empid)
   INNER JOIN awards a ON (u.empid = a.empid)
   HAVING distance < 25
   ORDER BY distance
) a
ORDER BY timestamp DESC

Answer 1

这是因为您的第一个 SELECT第二个SELECT有不同数量的列，因为你介绍了Distance在第 2 SELECT .

所以试着制作Distance在第一个查询中为 null 或 0，如下所示。

SELECT * FROM
(
   SELECT *, 0 as Distance
   FROM user u
   INNER JOIN employee e ON (u.empid = e.empid)
   INNER JOIN awards a ON (u.empid = a.empid)
   WHERE u.empid = 123

   UNION

   SELECT *, ( 3959 * acos( cos( radians(37) ) * cos( radians( lat ) ) * cos( radians( lng ) - radians(-122) )+ sin( radians(37) ) * sin( radians( lat ) ) ) ) AS distance
   FROM user u
   INNER JOIN employee e ON (u.empid = e.empid)
   INNER JOIN awards a ON (u.empid = a.empid)
   HAVING distance < 25
   ORDER BY distance
) a
ORDER BY timestamp DESC