Question

我必须从Common_CustomerComments表中获取一个描述，该描述具有最大优先级（最大优先级为3）和最大InsertDate

我使用了此查询

select TOP 1 Description 
from Common_CustomerComments 
WHERE CustomerCode = 1 
  AND Priority > 1 
ORDER BY Priority desc, InsertDate desc

但是我需要创建不带“ TOP”的查询，有人可以帮助我使用MAX（）函数创建查询

我尝试了此查询，但是对此有疑问：

SELECT Description 
FROM Common_CustomerComments 
WHERE CustomerCode = 1 
  and Id IN (SELECT MAX(Priority) 
             FROM Common_CustomerComments pr 
             JOIN (SELECT MAX(InsertDate) as maxdata))

Answer 1

我会使用ROW_NUMBER()：

select cc.Description 
from (select cc.*,
             row_number() over (partition by customercode order by priority desc, insertdate desc) as seqnum
      from Common_CustomerComments
      where CustomerCode = 1 and Priority > 1  
     ) cc
where seqnum = 1;

Answer 2

在通用中，您可以将subquery与 correlation 方法结合使用：

select cc.*
from Common_CustomerComments cc
where id = (select top 1 cc1.id
            from Common_CustomerComments cc1
            where cc1.customercode = cc.customercode 
            order by cc1.priority desc, cc1.insertdate desc
           );

但是，如果是，则假定id为PK（即主键），则等效方法为 MySQL

中的LIMIT子句

类似的东西：

 . . .
where id = (select cc1.id
            from Common_CustomerComments cc1
            where cc1.customercode = cc.customercode 
            order by cc1.priority desc, cc1.insertdate desc
            limit 1
            );

SQL查询，使用MAX（）代替TOP

2 个答案: