Question

我想从下面的查询2中选择WHERE (uid = {$uid} OR uid = **HERE** )其中**HERE**为cid的所有行。

查询1：

    SELECT * FROM `t_activities`
    WHERE (`uid` = {$uid} OR `uid` = **HERE** )
    AND `del` = 0
    GROUP BY `fid`
    ORDER BY `time` DESC 
    LIMIT 10

查询2：

SELECT `cid` FROM `t_con` WHERE `uid` = {$uid} AND `flag` = 1

Answer 1

SELECT * FROM `t_activities`
WHERE (`uid` = {$uid} OR `uid` in (SELECT `cid` 
                                   FROM `t_con` 
                                   WHERE `uid` = {$uid} AND `flag` = 1))
AND `del` = 0
GROUP BY `fid`
ORDER BY `time` DESC 
LIMIT 10

Answer 2

您也可以将其作为联接：

SELECT *
FROM `t_activities` ta left outer join
     (SELECT `cid` 
      FROM `t_con` 
      WHERE `uid` = {$uid} AND `flag` = 1)
     ) tc
     on ta = tc.cid
WHERE (`uid` = {$uid} OR tc.`uid` is not null) AND `del` = 0
GROUP BY `fid`
ORDER BY `time` DESC 
LIMIT 10

顺便说一下，作为一个SQL语句，“GROUP BY fid”看起来很奇怪。这在mysql中是允许的，但我认为这是一个不好的做法。明确你正在做的事情要好得多：

SELECT fid, min(<field1>) as Field1, . . .

这有助于防止在您返回查询或尝试修改查询时出错。

如何将这两个Select查询与OR案例组合在一起

2 个答案: