c# - 单个表达式中多个聚合值的 Linq-to-SQL 语句

Question

如何为以下 TSQL 编写 Linq-to-SQL 语句？

select 
  count(*),
  sum(Amount),
  avg(Amount),
  min(Amount),
  max(Amount) 
from 
  TableName

Answer 1

HACK ALERT，但它有效。尝试按照所有记录都共享的条件对您的记录进行分组:

var result = from g in db.Employees
        group g by g.Id.GetType() == typeof(int) into gg
        select new 
        {
            Count = gg.Count(),
            Sum = gg.Sum(x => x.Salary)
        };

这会生成 SQL:

SELECT COUNT(*) AS [Count], SUM([t1].[Salary]) AS [Sum]
FROM (
SELECT 1 AS [value], [t0].[Salary]
FROM [dbo].[Employee] AS [t0]
) AS [t1]
GROUP BY [t1].[value]

这里涉及一个子查询，但是嘿!这只是一次数据库旅行