Linq2Entities + Entity Framework查询优化：.Where（）vs. Linq where
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我对实体框架模型有一个Linq查询，类似于：
from e1 in context.Entity1
from e2 in context.Entity2
from e3summary in
from e3 in context.Entity3
where e3.Field1 = value // <-- this is the line in question
group e3 by new { e3.Field1, e3.Field2, e3.Field3 }
into e3group
select new
{
e3group.Key.Field1,
e3group.Key.Field2,
e3group.Key.Field3,
Total = e3group.Sum(o => o.Field4)
}
where
// conditions on e1 and joining e1, e2, and e3summary
...
select e1;
...
INNER JOIN (SELECT
[Extent3].[Field1] AS [K1],
[Extent3].[Field2] AS [K2],
[Extent3].[Field3] AS [K3],
SUM([Extent3].Field4] AS [A1]
FROM (SELECT
[e3].[ID] AS [ID],
[e3].[Field1] AS [Field1],
[e3].[Field2] AS [Field2],
[e3].[Field3] AS [Field3],
[e3].[Field4] AS [Field4],
[e3].[Field5] AS [Field5],
[e3].[Field6] AS [Field6],
[e3].[Field7] AS [Field7],
[e3].[Field8] AS [Field8]
FROM [dbo].[e3] AS [e3]) AS [Extent3]
WHERE ([Extent3].[Field1] = @p__linq__0)
GROUP BY [Extent3].[Field1], [Extent3].[Field2], [Extent3].[Field3] ) AS [GroupBy1]
...
from e3 in context.Entity3
where e3.Field1 = value // <-- this is the line in question
from e3 in context.Entity3.Where(e => e.Field1 = value)
...
FROM [dbo].[e3] AS [e3] WHERE [e3].Field1] = @p__linq__0) AS [Extent3]
GROUP BY [Extent3].[Field1], [Extent3].[Field2], [Extent3].[Field3] ) AS [GroupBy1]
没有找到相关结果
已邀请:
1 个回复
念炯
而第二个查询被评估为虚线语法具有优先权，因为它被当作单独的表达式子树，必须将其构造并附加到外部查询的表达式树上。您可以将其视为子查询，即使它不一定像您的示例所示那样最后还是子查询。