Question

我希望从两个表中合并记录，对它们进行排序，并从结果集中读取TOP行。

T1
--------
Id, Timestamp, Text1

T2
--------
Id, Timestamp, Text2

使用SQL可以这样做：

SELECT TOP 10 * FROM
(
    SELECT 
        [Timestamp], 
        [Text1] 

    FROM 
        T1

    UNION

    SELECT 
        [Timestamp], 
        [Text2]

    FROM 
        T2
) as x

ORDER BY [Timestamp]

问：如何使用EF linq执行该任务？

Answer 1

在执行Union操作之前，您需要具有相同属性名称和类型的匿名类型：

var t1List = from a in allT1
        select new
        {
            TimeStamp = a.TimeStamp,
            Text = a.Text1
        };
var t2List = from b in allT2
        select new
        {
            TimeStamp = b.TimeStamp,
            Text = b.Text2
        };

var result = t1List.Union(t2List).OrderBy(ab => ab.TimeStamp).Take(10);

Answer 2

如下：

var top10 = EFentity.t2.Union(EFentity.t1.ToList()).OrderBy(t=>t.Timestamp).ToList().Take(10);

EF。如何联合表，排序行和获取顶级实体？

2 个答案: