EF.如何联合表,排序行和获取顶级实体？

Question

我想从两个表中联合记录,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完成该任务？

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);