实体框架 6 和 LINQ - 重复记录

Question

我有一个标准的实体框架实现直接查询一个表，根本不涉及任何视图，代码如下：

var r = cxt.HistoricalQualityComponents.Where(f => f.ProducerID == activeProducer);

一切正常，我希望有 24 条记录，我得到 24 条记录。除了当我查看 r 的内容时，我看到了第一个返回的记录，重复了 24 次。我查看生成的 SQL 并直接针对数据库运行它，我得到 24 条唯一记录。我通过在 activeProducer 更改时观察内容，甚至在 LINQ 查询中应用排序来得出结论。我不知道如何解决这个问题。这发生在我的数据库中有两个表，但没有其他表。

我试图删除我的 .edmx 实体文件，我重命名了表（和生成的实体），并创建了一个完整的 .aspx 文件来处理实体。当然，我这样修改了查询：

var r = from h in cxt.HistoricalQualityComponents where h.ProducerId == activeProducer select h;

没有影响。

这可能完全不相关，但在（非常懒惰地）在两个结果集上尝试以下操作后，我注意到了这种行为：

r.Sort(delegate(HistoricalQualityComponents c1, HistoricalQualityComponents c2) { return Convert.ToDateTime(c2.Pickup_Date).CompareTo(Convert.ToDateTime(c1.Pickup_Date)); });

在这一点上，我只想回到一个干净的状态，这样我就可以实现一个模型类，它将数据存储到一个正确类型的对象中，我可以更适当地对其进行排序，但不知所措下一步要去哪里。

更新：生成的 SQL 如下：

SELECT 
    [Extent1].[RcdID] AS [RcdID], 
    [Extent1].[FieldRepID] AS [FieldRepID], 
    [Extent1].[ProducerID] AS [ProducerID], 
    [Extent1].[MonthYear_PK] AS [MonthYear_PK], 
    [Extent1].[Weight] AS [Weight], 
    [Extent1].[Fat] AS [Fat], 
    [Extent1].[Protein] AS [Protein], 
    [Extent1].[Lactose] AS [Lactose], 
    [Extent1].[SNF] AS [SNF], 
    [Extent1].[StateLeuc] AS [StateLeuc], 
    [Extent1].[Leuc] AS [Leuc], 
    [Extent1].[StateRaw] AS [StateRaw], 
    [Extent1].[Raw] AS [Raw], 
    [Extent1].[RawBracket] AS [RawBracket], 
    [Extent1].[PI] AS [PI], 
    [Extent1].[PIBracket] AS [PIBracket], 
    [Extent1].[lpc_avg] AS [lpc_avg], 
    [Extent1].[Water] AS [Water], 
    [Extent1].[AB] AS [AB], 
    [Extent1].[SED] AS [SED], 
    [Extent1].[mun] AS [mun], 
    [Extent1].[LStd] AS [LStd], 
    [Extent1].[RStd] AS [RStd], 
    [Extent1].[PStd] AS [PStd], 
    [Extent1].[SStd] AS [SStd], 
    [Extent1].[QualPremRate] AS [QualPremRate], 
    [Extent1].[QualPremAmt] AS [QualPremAmt], 
    [Extent1].[FYTDQualScore] AS [FYTDQualScore], 
    [Extent1].[FYTDQualPrem] AS [FYTDQualPrem], 
    [Extent1].[FYTDAvgQualPremRate] AS [FYTDAvgQualPremRate], 
    [Extent1].[OtherSolids] AS [OtherSolids], 
    [Extent1].[AshFactor] AS [AshFactor], 
    [Extent1].[ash_wtd_avg] AS [ash_wtd_avg], 
    [Extent1].[fat_wtd_avg] AS [fat_wtd_avg], 
    [Extent1].[leuc_wtd_avg] AS [leuc_wtd_avg], 
    [Extent1].[protein_wtd_avg] AS [protein_wtd_avg], 
    [Extent1].[os_wtd_avg] AS [os_wtd_avg], 
    [Extent1].[snf_wtd_avg] AS [snf_wtd_avg], 
    [Extent1].[iodine_wtd_avg] AS [iodine_wtd_avg]
FROM (SELECT 
    [HistoricalQualityComponents].[RcdID] AS [RcdID], 
    [HistoricalQualityComponents].[FieldRepID] AS [FieldRepID], 
    [HistoricalQualityComponents].[ProducerID] AS [ProducerID], 
    [HistoricalQualityComponents].[MonthYear_PK] AS [MonthYear_PK], 
    [HistoricalQualityComponents].[Weight] AS [Weight], 
    [HistoricalQualityComponents].[Fat] AS [Fat], 
    [HistoricalQualityComponents].[Protein] AS [Protein], 
    [HistoricalQualityComponents].[Lactose] AS [Lactose], 
    [HistoricalQualityComponents].[SNF] AS [SNF], 
    [HistoricalQualityComponents].[StateLeuc] AS [StateLeuc], 
    [HistoricalQualityComponents].[Leuc] AS [Leuc], 
    [HistoricalQualityComponents].[StateRaw] AS [StateRaw], 
    [HistoricalQualityComponents].[Raw] AS [Raw], 
    [HistoricalQualityComponents].[RawBracket] AS [RawBracket], 
    [HistoricalQualityComponents].[PI] AS [PI], 
    [HistoricalQualityComponents].[PIBracket] AS [PIBracket], 
    [HistoricalQualityComponents].[lpc_avg] AS [lpc_avg], 
    [HistoricalQualityComponents].[Water] AS [Water], 
    [HistoricalQualityComponents].[AB] AS [AB], 
    [HistoricalQualityComponents].[SED] AS [SED], 
    [HistoricalQualityComponents].[mun] AS [mun], 
    [HistoricalQualityComponents].[LStd] AS [LStd], 
    [HistoricalQualityComponents].[RStd] AS [RStd], 
    [HistoricalQualityComponents].[PStd] AS [PStd], 
    [HistoricalQualityComponents].[SStd] AS [SStd], 
    [HistoricalQualityComponents].[QualPremRate] AS [QualPremRate], 
    [HistoricalQualityComponents].[QualPremAmt] AS [QualPremAmt], 
    [HistoricalQualityComponents].[FYTDQualScore] AS [FYTDQualScore], 
    [HistoricalQualityComponents].[FYTDQualPrem] AS [FYTDQualPrem], 
    [HistoricalQualityComponents].[FYTDAvgQualPremRate] AS [FYTDAvgQualPremRate], 
    [HistoricalQualityComponents].[OtherSolids] AS [OtherSolids], 
    [HistoricalQualityComponents].[AshFactor] AS [AshFactor], 
    [HistoricalQualityComponents].[ash_wtd_avg] AS [ash_wtd_avg], 
    [HistoricalQualityComponents].[fat_wtd_avg] AS [fat_wtd_avg], 
    [HistoricalQualityComponents].[leuc_wtd_avg] AS [leuc_wtd_avg], 
    [HistoricalQualityComponents].[protein_wtd_avg] AS [protein_wtd_avg], 
    [HistoricalQualityComponents].[os_wtd_avg] AS [os_wtd_avg], 
    [HistoricalQualityComponents].[snf_wtd_avg] AS [snf_wtd_avg], 
    [HistoricalQualityComponents].[iodine_wtd_avg] AS [iodine_wtd_avg]
FROM 
    [dbo].[HistoricalQualityComponents] AS [HistoricalQualityComponents]) AS [Extent1]
WHERE 
    [Extent1].[ProducerID] = @p__linq__0

Answer 1

如果您的实体模型中的键与数据库表中的键不匹配，则可能会发生这种情况。

例如，如果数据库中的键是由 (RcdID, FieldRepID) 组成的复合键，但在您的模型实体中，只有 RcdID 被定义为键，并且您运行的查询将返回三行，其值为 (1, 1)、@987654324 @ 和 (1, 3) 你可能会得到一个实体列表，其中包含值 (1, 1) 三次。

原因是 EF 仅“看到”该对的第一部分 1 作为密钥。该键值被返回 3 次。因为 EF 仅将每个键的一个对象附加到上下文，所以第一行被具体化为具有键 1 的实体，但对于第二行和第三行，没有新的实体被具体化。而是将第一行的已附加实体第二次和第三次添加到结果列表中。

长话短说：检查实体模型中定义的键是否与数据库模式中的键匹配。