Question

如何使用linq模拟Derived Table

考虑此代码：

SELECT * FROM (SELECT * FROM Mytbl) AS tmp WHERE tmp.ID=1

我如何用Linq写这个？

感谢

编辑1：

如何将其转换为linq？：

select 
convert( decimal(10,1), ROUND(A.c2*100,8)),
convert( decimal(10,1), ROUND(A.c3*100,8))
from
(
SELECT 
    (
        SELECT CONVERT(INT, COUNT(ID))
        FROM tbl
        WHERE (col06 >= @param_Min and col06 <= @param_Max )

    )
    /  
    (
        SELECT CONVERT(INT, COUNT(ID))
        FROM tbl
        WHERE (col06 >= 10 )                    
    ) as c2
    (
        SELECT CONVERT(INT, COUNT(ID))
        FROM tbl
        WHERE (col06 >= @param_Min and col06 <= @param_Max )
            AND (col03 = 1)
    )
    /  
    (
        SELECT CONVERT(INT, COUNT(ID))
        FROM tbl
        WHERE (col06 >= 10 ) AND (col03 = 1)    
    ) as c3
) AS A

Answer 1

**SELECT * FROM (SELECT * FROM Mytbl) AS tmp WHERE tmp.ID=1**

Linq版

var result = db.MyTbl.Where( x => x.ID == 1);

2

 var query = 
                let c1= from b in db.MyTbl
                                  where b.col06 >= @param_Min//some condition
                                  select b.ID
                let c2= from b in db.MyTbl
                                  where b.col06 >= 10//some condition
                                  select b.ID
                let c3=from b in db.MyTbl
                                   where b.col06 >= @param_Min//some condition
                                  select b.ID

                select new
                { 
                    c2.ID,//perform Round and other operation on this  
                    c3.ID//perform Round and other operation on this 

                };

Answer 2

WITH(NOLOCK)无法在LINQ-to-Entities中实现，因此您应该将其包装在存储过程中并调用它。

通常这是计算而不是数据集检索，所以它不太适合Linq到实体。使用EF计算时，应在应用程序中完成，因此应分别调用四个子查询并在应用程序中计算结果。作为替代方案，您可以使用存储过程。

如何使用linq到Entities来模拟Derived表

2 个答案: