Question

我正在努力获得指定记录的排名，我在这段代码中取得了一些成功：

SELECT `rank`
FROM
   (
     select @rownum:=@rownum+1 `rank`, p.* 
     from TableName  p, (SELECT @rownum:=0) r 
     order by point DESC
   ) s
   WHERE names = 'house'

（See the schema here.）

此SQL查询有效，但如果我想根据city_id和name获取结果，我必须使用两个where子句，然后代码不起作用。

我想仅为其城市获得house等级。我怎么能这样做？

Answer 1

我想只为其城市获得“房子”的等级

您可以通过引入另一个变量来跟踪城市来实现这一目标：

SELECT `rank`
FROM (select p.*,
             (@rn := if(@c = city, @rn + 1,
                        if(@c := city, 1, 1)
                       )
             ) as rank
      from TableName  p CROSS JOIN
           (SELECT @rn := 0, @c := -1) params
      order by city_id, point DESC
     ) s
 WHERE names = 'house' ;

如果你知道“house”只出现在数据中一次，你也可以使用原始查询进行调整：

SELECT `rank`
FROM (select p.*, (@rn := @rn + 1) as rank
      from TableName  p CROSS JOIN
           (SELECT @rn := 0) params
      where city_id = (select city_id from TableName t2 where t2.names = 'house')
      order by point DESC
     ) s
 WHERE names = 'house' ;

使用两个where子句获取记录的等级

1 个答案: