显示mysql中的行数选择

Question

我有这样的声明：

SELECT count(s.name), s.name, avg(a.rate),  @curRank := @curRank + 1 AS rank 
FROM `avatec_objects_comments` as a, avatec_objects as s, (SELECT @curRank := 0) r
WHERE a.oid =s.id and s.status=0 
GROUP BY s.name 
ORDER BY  avg(a.rate) desc, count(s.name) desc

这是我想要的结果（见侧面的数字）

如何根据count(s.name)和avg(a.rate)设置上述所需结果中的排名？

Answer 1

MySQL似乎在使用group by变量时遇到问题。解决方案是使用子查询。此外，您可以使用显式join语法来改进查询：

SELECT cnt, name, avgrate,
       (@curRank := @curRank + 1) AS rank 
FROM (SELECT count(o.name) as cnt, o.name, avg(oc.rate) as avgrate, 
      FROM avatec_objects o JOIN
           avatec_objects_comments oc
           ON oc.oid = o.id 
      WHERE o.status = 0
      GROUP BY o.name
     ) oc CROSS JOIN
     (SELECT @curRank := 0) vars
ORDER BY  avgrate desc, cnt desc;

Answer 2

您必须嵌套查询。订购将作为此查询中的最后一个操作完成，因此它将始终替换您的排名。请查看以下内容：

SET @rank=0;
SELECT t1.*, @rank:=@rank+1 AS rank FROM 
  (SELECT count(s.name), s.name, avg(a.rate) 
   FROM `avatec_objects_comments` as a, avatec_objects as s
   WHERE a.oid =s.id and s.status=0 
   GROUP BY s.name 
   ORDER BY  avg(a.rate) desc, count(s.name) desc)) t1;

在此查询中，您将获得所需的数据（将被选中，分组并排序十个），然后它只会将数据添加到准备阅读的数据中。