.net 4.5 和实体框架中的外部应用答案

【问题标题】：OUTER APPLY in .net 4.5 and Entity Framework.net 4.5 和实体框架中的外部应用
【发布时间】：2013-06-13 09:11:52
【问题描述】：

安装.Net 4.5后，EF生成的查询出现问题。 linq 中对.Net 4.0 的相同查询可以正常工作。我正在使用 Firebird 数据库，它不支持命令 OUTER APPLY。有什么方法可以修改以下查询 linq，使其在 .Net 4.5 中运行？

当前 linq 查询：

int[] AROIds = (from x in context.RISK_T_ASSESS_HIST
               where (x.ID_RISKOBJECT.HasValue && x.F_CREATEDON >= Freq.StartDate 
               && x.F_CREATEDON <= Freq.EndDate)
               group x by x.ID_RISKOBJECT into gr
               let lastCreated = gr.Max(p => p.F_CREATEDON)
               select new
               {
                 ObjId = gr.Key
                 , LastStatus = gr.Where(p => p.F_CREATEDON == lastCreated 
                   && p.ID_RISKOBJECT == gr.Key)
                   .Select(p => p.F_STATUS).FirstOrDefault()
               }).Where(x => x.LastStatus == 0 || x.LastStatus == 1)
               .Select(x => x.ObjId.Value).ToArray();

为生成的 SQL。净 4.5：

SELECT
"Project1"."ID_RISKOBJECT" AS "ID_RISKOBJECT"
FROM (SELECT
    "GroupBy1"."A1" AS "C1",
    "GroupBy1"."K1" AS "ID_RISKOBJECT"
    FROM ( SELECT
        "Extent1"."ID_RISKOBJECT" AS "K1",
        MAX("Extent1"."F_CREATEDON") AS "A1"
        FROM "RISK_T_ASSESS_HIST" AS "Extent1"
        WHERE (("Extent1"."ID_RISKOBJECT" IS NOT NULL)
        AND ("Extent1"."F_CREATEDON" >= 2013-04-17))
        AND ("Extent1"."F_CREATEDON" <= 2013-04-17)
        GROUP BY "Extent1"."ID_RISKOBJECT"
    ) AS "GroupBy1" ) AS "Project1"
OUTER APPLY (SELECT FIRST (1)
    "Extent2"."F_STATUS" AS "F_STATUS"
    FROM "RISK_T_ASSESS_HIST" AS "Extent2"
    WHERE (((("Extent2"."ID_RISKOBJECT" IS NOT NULL)
    AND ("Extent2"."F_CREATEDON" >= 2013-04-17))
    AND ("Extent2"."F_CREATEDON" <= @2013-04-17))
    AND (("Project1"."ID_RISKOBJECT" = "Extent2"."ID_RISKOBJECT") OR (("Project1"."ID_RISKOBJECT" IS NULL)
    AND ("Extent2"."ID_RISKOBJECT" IS NULL)))) AND (("Extent2"."F_CREATEDON" = "Project1"."C1")
    AND ("Extent2"."ID_RISKOBJECT" = "Project1"."ID_RISKOBJECT")) ) AS "Limit1"
WHERE (0 = "Limit1"."F_STATUS") OR (1 = "Limit1"."F_STATUS")

【问题讨论】：

我正在使用 Firebird 数据库，它不支持命令 OUTER APPLY 听起来是提供商的问题，您使用的是正确的吗？
欺骗stackoverflow.com/questions/16650954/…，但我建议不要关闭这个问题，因为另一个问题本质上已将“不要安装.NET 4.5”标记为答案......
我需要安装 .net 4.5。即使安装在环境.Net 4.5?上，我能否让EF在4.0中工作
不是供应商：Firebird bugtrack

标签： .net sql linq entity-framework linq-to-entities

【解决方案1】：

好的。唯一的解决方案，这是我在阅读列表的初始表时发现的。不幸的是，不是我的意思，但它有效。

 AIds = (from x in 
        (
           context.RISK_T_ASSESS_HIST.Where(x => x.ID_RISKOBJECT.HasValue && x.F_CREATEDON >= Freq.StartDate && x.F_CREATEDON <= Freq.EndDate)
           .Select(x => new { x.ID_RISKOBJECT, x.F_CREATEDON, x.F_STATUS }).ToList()
        )      
        group x by x.ID_RISKOBJECT into gr
        let lastCreated = gr.Max(p => p.F_CREATEDON)
        select new
        {
           ObjId = gr.Key
           ,
           LastStatus = gr.Where(p => p.F_CREATEDON == lastCreated && p.ID_RISKOBJECT == gr.Key).Select(p => p.F_STATUS).FirstOrDefault()
        }).Where(x => x.LastStatus == 0 || x.LastStatus == 1).Select(x => x.ObjId.Value).ToArray();

这个问题实体框架，将在他们的论坛上作为错误传递。

【讨论】：