Question

我想为每第n行查询一个EF 4实体集，这样我得到的结果不会超过x。例如，给定一组1000个名字，给我每100个名字（按名称排序），这样我就有10个结果。

LINQ to Entities能以任何有效的方式实现这种事吗？

Answer 1

不在L2S中，但您可以使用ExecuteStoreQuery执行此操作：

你想要SQL：

SELECT 
[Project1].[C1] AS [C1], 
[Project1].[DepartmentId] AS [DepartmentId], 
[Project1].[Code] AS [Code], 
[Project1].[DepartmentName] AS [DepartmentName]
FROM ( SELECT [Project1].[DepartmentId] AS [DepartmentId], [Project1].[Code] AS [Code], [Project1].[DepartmentName] AS [DepartmentName], [Project1].[C1] AS [C1], row_number() OVER (ORDER BY [Project1].[DepartmentName] ASC) AS [row_number]
    FROM ( SELECT 
        [Extent1].[DepartmentId] AS [DepartmentId], 
        [Extent1].[Code] AS [Code], 
        [Extent1].[DepartmentName] AS [DepartmentName]
        1 AS [C1]
        FROM [dbo].[Department] AS [Extent1]
    )  AS [Project1]
)  AS [Project1]
WHERE [Project1].[row_number] % 4 = 0          
ORDER BY [Project1].[DepartmentName] ASC

（或者用param代替我的硬编码4。）

然后代码如下：

var q = Context.ExecuteStoreQuery<Foo>(
    sql, params);

如何查询有序实体集中的每个第n个值？

1 个答案: