在 SQL 中从 Count() 选择最大值时出错

Question

我在 SQL 服务器中应用 MAX 和 COUNT 时遇到错误，即使我的代码是正确的。请在我出错的地方帮助我

显示Sales.Invoicestable

中打包物品数量最多的人id

select 
    PackedByPersonID, count(PackedByPersonID) 
from 
    Sales.Invoices 
group by 
    PackedByPersonID 
having 
    count(PackedByPersonID) = (select max(max_count) 
                               from 
                                   (select PackedByPersonID, count(PackedByPersonID) max_count 
                                    from Sales.Invoices 
                                    group by PackedByPersonID))

虽然执行 SQL 无法识别代码中的 max_count.. 因为它带有红色下划线并且显示“无效的列名称 'max_count'”

错误：

Msg 102, Level 15, State 1, Line 8
Incorrect syntax near ')'

Answer 1

我建议为此使用 window 函数或 TOP。但是您的语法错误是因为 FROM 子句中的所有子查询都需要 SQL Server 中的别名。所以：

select PackedByPersonID, count(PackedByPersonID)
from Sales.Invoices 
group by PackedByPersonID 
having count(PackedByPersonID) = (
           select MAX(max_count)
           from (select PackedByPersonID, count(PackedByPersonID) max_count
                 from Sales.Invoices 
                 group by PackedByPersonID
                ) i
------------------^ the table alias
          )

编写查询的更简单、更有效的方法是：

select top (1) with ties PackedByPersonID, count(*)
from Sales.Invoices 
group by PackedByPersonID 
order by count(*) desc;

在 SQL 中从 Count() 选择最大值时出错

Getting error while Selecting MAX value from Count() in SQL

sql

sql-server

mssql-jdbc