我可以计算名称在第一个查询中出现的次数的子查询

Question

这是我目前的代码：

select Name, ECU, Identifier, Value, Max(Filetime) as "Filetime"
from dbo.view_1
where ECU='EBS7' and Identifier='88' and Value='2459579' or identifier ='87' and Value='2431629'
group by Name, ECU, Identifier, Value
ORDER BY
    MAX(Name) ASC

这是我得到的结果：

我想要某种子查询或计算名称出现次数的东西。可以看到Agon出现了两次，Apollo Akka只出现了一次

关于我应该写什么的任何提示？

Answer 1

您可以为此使用相关子查询：

Select Name, ECU, Identifier, Value,
       Max(Filetime) as "Filetime",
       (select count(*)
       from dbo.view_1 t2 
       where t2.Name = t1.Name and
             ECU ='EBS7' and 
             ((Identifier='88' and Value='2459579') or 
             (identifier ='87' and Value='2431629')) as cnt
from dbo.view_1 t1
where ECU ='EBS7' and 
      ((Identifier='88' and Value='2459579') or 
      (identifier ='87' and Value='2431629'))
group by Name, ECU, Identifier, Value
ORDER BY MAX(Name) ASC

Answer 2

我不知道 MySQL（您实际使用的是哪个产品？），但在 MS-SQL 这个

ORDER BY MAX(Name) ASC

甚至无法编译。您不能按不在 SELECT 列表中的列排序。

如果您想获得原始结果集，名称的频率在集合本身中，并且您使用的是 MS-SQL，您可以使用 CTE：

WITH theset AS 
(select Name, ECU, Identifier, Value, Max(Filetime) as "Filetime"
from dbo.view_1
where ECU='EBS7' and Identifier='88' and Value='2459579' or identifier ='87' and Value='2431629'
group by Name, ECU, Identifier, Value)

SELECT set.*,CountNames.NameCount
FROM
    theset set
INNER JOIN
    (SELECT Name,Count(*) AS NameCount FROM theset GROUP BY Name) CountNames
ON set.Name=CountNames.Name

我可以计算名称在第一个查询中出现的次数的子查询

Subquery where I can count number of times a name appears from the first query

sql

sql-server

subquery