用于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

单独提取值可能更容易，但您可以使用匿名类型。

var aggregates = new { 
Count = context.TableName.Count(), 
Sum = context.TableName.Sum(t => t.Amount), 
Avg = context.TableName.Avg(t => t.Amount), 
Min = context.TableName.Min(t => t.Amount), 
Max = context.TableName.Max(t => t.Amount) 
}; 

Answer 2

你可以这样做：

var result = new 
{ 
    Count = db.TableName.Count(), 
    Sum = db.TableName.Sum(r => r.Amount), 
    Average = db.TableName.Avg(r => r.Amount), 
    Min = sb.TableName.Min(r => r.Amount), 
    Max = db.TableName.Max(r => r.Amount)   
} 

Answer 3

HACK ALERT，但它的作品。通过一个条件，要力图您记录所有的人分享：

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) 
     }; 

这将生成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] 

有涉及子查询，但嘿！它只有一分贝旅行