Question

我想知道每个部门注册最多的用户，关闭了最。这些数据分布在3个表中 - Department和Closed在BATCH中表，STORE表中的registered_by和ACCOUNT表中的用户名。

我正在尝试使用count和max聚合函数来获取此信息。

这是我写的查询：

 SELECT
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username,
     COUNT(s.regsitered_by) As "Total Regsitered",
     COUNT(b.closed_by) As "Total Closed"

    FROM [db].[store] as s
    LEFT JOIN [db].[batch] b on b.id = s.batch_id
    LEFT JOIN [db].[accounts] as a on a.id = b.closed_by

    WHERE registered_by = (select max(regsitered_by)from [db].[store]) AND
    closed_by = (select max(closed_by)from [db].[batch])

    group by  
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username

非常感谢任何建议。

我也试图使用临时表来保存结果，但这不是很有帮助

 SELECT
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username,
     COUNT(s.regsitered_by) AS "Total Regsitered",
     COUNT(b.closed_by) AS "Total Closed"

     INTO #TEMP1

    FROM [db].[store] AS s
    LEFT JOIN [db].[batch] AS b ON b.id = s.batch_id
    LEFT JOIN [db].[accounts] AS a ON a.id = b.closed_by

    GROUP BY
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username

    SELECT *
    FROM #temp1
    WHERE registered_by = (SELECT MAX(regsitered_by)FROM [db].[store]) AND
    closed_by = (SELECT MAX(closed_by)From [db].[batch])

    DROP TABLE #temp1

Answer 1

在where子句中，您正在检查以下条件..

WHERE registered_by = (select max(regsitered_by)from [db].[store]) AND
closed_by = (select max(closed_by)from [db].[batch])

这将在计数之前应用，因此您可能无法获得准确的结果。将该条款移至

 SELECT
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username,
     COUNT(s.regsitered_by) As "Total Regsitered",
     COUNT(b.closed_by) As "Total Closed"
    FROM [db].[store] as s
    LEFT JOIN [db].[batch] b on b.id = s.batch_id
    LEFT JOIN [db].[accounts] as a on a.id = b.closed_by
    group by  
     b.department_id, 
     s.regsitered_by, 
     b.closed_by, 
     a.username
having 
 COUNT(s.regsitered_by)=(select max(regsitered_by)from [db].[store])
 and
 COUNT(s.closed_by)=(select max(closed_by)from [db].[batch])

Answer 2

不允许排名（rank，dense_rank，row_number）？那么，这里是如何让每个部门最关闭的人：

select counts.department_id, counts.closed_by
from
(
  select department_id, closed_by, count(*) as cnt
  from batch
  group by department_id, closed_by
) counts
join
(
  select department_id, max(cnt) as cnt
  from
  (
    select department_id, count(*) as cnt
    from batch
    group by department_id, closed_by
  ) counts
) maxcounts on maxcounts.department_id = counts.department_id 
            and maxcounts.cnt = counts.cnt

对department_id, registered_by执行相同操作，您必须加入两个表batch和store。

然后：

select 
  coalesce(c.department_id, r.department_id) as department_id,
  (select username from account a where a.id = c.closed_by) as closer,
  (select username from account a where a.id = c.registered_by) as registerer
from (<close_by query>) c
full outer join (<registered_by query>) r on r.department_id = c.department_id;

我应该补充一点，如果每个部门有多个最大关闭器或注册器，这不是最佳选择。对于X部门，我们有以下注册人：

user   cnt
emp1   20
emp2   30
emp3   30

以及以下关闭者;

user   cnt
emp1   15
emp2   10
emp4   15

然后我们得到：

dept   max_registerer   max_closer
X      emp2             emp1
X      emp2             emp4
X      emp3             emp1
X      emp3             emp4

因此，您可能希望将此结果汇总到

dept   max_registerer   max_closer
X      emp2, emp3       emp1, emp4

例如，

。（如果是这样，请查看如何在SQL Server中模仿GROUP_CONCAT。）

不使用Ranks或Top的SQL查询计数和最大值

2 个答案: