获得创纪录的等级用两个where子句

Question

我试图让指定的记录的级别，我有一些成功与此代码：

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查询工作，但如果我想根据city_id和name得到结果，我必须使用两个where子句，然后代码不起作用。

我想获得排名house只为它的城市。我怎样才能做到这一点？

Answer 1

我想要得到的“家”排名不仅是因为它的城市

您可以通过引入另一个变量来跟踪城市的做到这一点：

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' ; 

你也可以如果你知道“房子”只在数据中出现一次，请使用原始查询：

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' ;