C# 当数据库中有数据时，查询不返回任何内容_C#_.net_Entity Framework_Tsql_Linq To Entities

C# 当数据库中有数据时，查询不返回任何内容

c# .net entity-framework tsql

C# 当数据库中有数据时，查询不返回任何内容,c#,.net,entity-framework,tsql,linq-to-entities,C#,.net,Entity Framework,Tsql,Linq To Entities,我使用EntityFramework 4+生成的POCO，并禁用延迟加载假设存在名为Table1、Table2、Table3和Table4的SQL表，并假设它们包含一些数据。假设这些表的简化POCO表示形式如下所示： public class Table1 { public int ID; public DateTime TableDate; public int Table2ID; public Table2 Table2; public IColl

我使用EntityFramework 4+生成的POCO，并禁用延迟加载
假设存在名为Table1、Table2、Table3和Table4的SQL表，并假设它们包含一些数据。
假设这些表的简化POCO表示形式如下所示：

public class Table1
{
    public int ID;
    public DateTime TableDate;
    public int Table2ID;
    public Table2 Table2;
    public ICollection<Table3> Table3s;
}

public class Table2
{
    public int ID;
    public string SomeString;
    public int Table4ID;
    public Table4 Table4;
}

public class Table3
{
    public int ID;
    public int Table1ID;
    public Table1 Table1;
    public decimal SomeDecimal;
}

public decimal Table4
{
    public int ID;
    public string SomeName;
}

EF将生成以下SQL语句：

exec sp_executesql N'SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[TableDate] AS [TableDate], 
[Extent1].[Table2ID] As [Table2ID]
FROM [dbo].[Table1] AS [Extent1]
WHERE ([Extent1].[TableDate] >= @p__linq__0)',N'@p__linq__0 datetime2(7)',@p__linq__0='0001-01-01 00:00:00'

exec sp_executesql N'SELECT 
[Project1].[ID2] AS [ID], 
[Project1].[ID] AS [ID1], 
[Project1].[TableDate] AS [TableDate], 
[Project1].[ID1] AS [ID2], 
[Project1].[SomeString] AS [SomeString], 
[Project1].[Table4ID] AS [Table4ID], 
[Project1].[ID3] AS [ID3], 
[Project1].[SomeName] AS [SomeName], 
[Project1].[ID4] AS [ID4], 
[Project1].[SomeDecimal] AS [SomeDecimal], 
[Project1].[Table1ID] AS [Table1ID]
FROM ( SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[TableDate] AS [TableDate], 
[Extent2].[ID] AS [ID1], 
[Extent2].[SomeString] AS [SomeString], 
[Extent2].[Table4ID] AS [Table4ID], 
[Extent3].[ID] AS [ID2], 
[Extent4].[ID] AS [ID3], 
[Extent4].[SomeName] AS [SomeName], 
[Extent5].[ID] AS [ID4], 
[Extent5].[SomeDecimal] AS [SomeDecimal], 
[Extent5].[Table1ID] AS [Table1ID], 
CASE WHEN ([Extent5].[ID] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
FROM     [dbo].[Table1] AS [Extent1]
INNER JOIN [dbo].[Table2] AS [Extent2] ON [Extent1].[Table2ID] = [Extent2].[ID]
LEFT OUTER JOIN [dbo].[Table2] AS [Extent3] ON [Extent1].[Table2ID] = [Extent3].[ID]
LEFT OUTER JOIN [dbo].[Table4] AS [Extent4] ON [Extent3].[Table4ID] = [Extent4].[ID]
LEFT OUTER JOIN [dbo].[Table3] AS [Extent5] ON [Extent1].[ID] = [Extent5].[Table1ID]
WHERE ([Extent1].[TableDate] >= @p__linq__0)
)  AS [Project1]
ORDER BY [Project1].[ID2] ASC, [Project1].[ID] ASC, [Project1].[ID1] ASC, [Project1].[ID3] ASC, [Project1].[C1] ASC',N'@p__linq__0 datetime2(7)',@p__linq__0='0001-01-01 00:00:00'

查询将返回预期的数据。
但是，如果将执行以下代码：

Database DB = new Database(); // object context
var result = DB.Table1
    .Where(x => x.TableDate >= DateTime.MinValue);

Database DB = new Database(); // object context
var result = DB.Table1
    .Include("Table2")
    .Include("Table2.Table4")
    .Include("Table3")
    .Where(x => x.TableDate >= DateTime.MinValue);

EF将生成以下SQL语句：

exec sp_executesql N'SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[TableDate] AS [TableDate], 
[Extent1].[Table2ID] As [Table2ID]
FROM [dbo].[Table1] AS [Extent1]
WHERE ([Extent1].[TableDate] >= @p__linq__0)',N'@p__linq__0 datetime2(7)',@p__linq__0='0001-01-01 00:00:00'

exec sp_executesql N'SELECT 
[Project1].[ID2] AS [ID], 
[Project1].[ID] AS [ID1], 
[Project1].[TableDate] AS [TableDate], 
[Project1].[ID1] AS [ID2], 
[Project1].[SomeString] AS [SomeString], 
[Project1].[Table4ID] AS [Table4ID], 
[Project1].[ID3] AS [ID3], 
[Project1].[SomeName] AS [SomeName], 
[Project1].[ID4] AS [ID4], 
[Project1].[SomeDecimal] AS [SomeDecimal], 
[Project1].[Table1ID] AS [Table1ID]
FROM ( SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[TableDate] AS [TableDate], 
[Extent2].[ID] AS [ID1], 
[Extent2].[SomeString] AS [SomeString], 
[Extent2].[Table4ID] AS [Table4ID], 
[Extent3].[ID] AS [ID2], 
[Extent4].[ID] AS [ID3], 
[Extent4].[SomeName] AS [SomeName], 
[Extent5].[ID] AS [ID4], 
[Extent5].[SomeDecimal] AS [SomeDecimal], 
[Extent5].[Table1ID] AS [Table1ID], 
CASE WHEN ([Extent5].[ID] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1]
FROM     [dbo].[Table1] AS [Extent1]
INNER JOIN [dbo].[Table2] AS [Extent2] ON [Extent1].[Table2ID] = [Extent2].[ID]
LEFT OUTER JOIN [dbo].[Table2] AS [Extent3] ON [Extent1].[Table2ID] = [Extent3].[ID]
LEFT OUTER JOIN [dbo].[Table4] AS [Extent4] ON [Extent3].[Table4ID] = [Extent4].[ID]
LEFT OUTER JOIN [dbo].[Table3] AS [Extent5] ON [Extent1].[ID] = [Extent5].[Table1ID]
WHERE ([Extent1].[TableDate] >= @p__linq__0)
)  AS [Project1]
ORDER BY [Project1].[ID2] ASC, [Project1].[ID] ASC, [Project1].[ID1] ASC, [Project1].[ID3] ASC, [Project1].[C1] ASC',N'@p__linq__0 datetime2(7)',@p__linq__0='0001-01-01 00:00:00'

查询将不返回任何内容

为什么会发生这种情况

编辑

以下是创建上述表的SQL语句：

CREATE TABLE [dbo].[Table1](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Table2ID] [int] NOT NULL,
[TableDate] [date] NOT NULL,
 CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED 
(
[ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

ALTER TABLE [dbo].[Table1]  WITH NOCHECK ADD  CONSTRAINT [FK_Table1_Table2] FOREIGN KEY([Table2ID])
REFERENCES [dbo].[Table2] ([ID])

ALTER TABLE [dbo].[Table1] CHECK CONSTRAINT [FK_Table1_Table2]

CREATE TABLE [dbo].[Table2](
[ID] [int] NOT NULL,
[SomeString] [nvarchar](50) NOT NULL,
[Table4ID] [int] NULL,
 CONSTRAINT [PK_Table2] PRIMARY KEY CLUSTERED 
(
[ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

ALTER TABLE [dbo].[Table2]  WITH NOCHECK ADD  CONSTRAINT [FK_Table2_Table4] FOREIGN KEY([Table4ID])
REFERENCES [dbo].[Table4] ([ID])
ON UPDATE CASCADE

ALTER TABLE [dbo].[Table2] CHECK CONSTRAINT [FK_Table2_Table4]

CREATE TABLE [dbo].[Table3](
[ID] [int] IDENTITY(1,1) NOT NULL,
[SomeDecimal] [decimal](18, 4) NOT NULL,
[Table1ID] [int] NOT NULL,
 CONSTRAINT [PK_Table3] PRIMARY KEY CLUSTERED 
(
[ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

ALTER TABLE [dbo].[Table3]  WITH NOCHECK ADD  CONSTRAINT [FK_Table3_Table1] FOREIGN KEY([Table1ID])
REFERENCES [dbo].[Table1] ([ID])
ON DELETE CASCADE

ALTER TABLE [dbo].[Table3] CHECK CONSTRAINT [FK_Table3_Table1]

CREATE TABLE [dbo].[Table4](
[ID] [int] NOT NULL,
[SomeName] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_Table4] PRIMARY KEY CLUSTERED 
(
[ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

编辑2

此查询也不会返回任何记录，可以作为一个简单的示例：

Database DB = new Database();
var result = DB.Table1
    .Include("Table2")
    .Where(x => x.TableDate >= DateTime.MinValue);

生成的SQL:

exec sp_executesql N'SELECT 
[Extent1].[ID] AS [ID], 
[Extent1].[Table2ID] AS [Table2ID], 
[Extent1].[TableDate] AS [TableDate], 
[Extent2].[ID] AS [ID1], 
[Extent2].[SomeString] AS [SomeString], 
[Extent2].[Table4ID] AS [Table4ID], 
FROM  [dbo].[Table1] AS [Extent1]
INNER JOIN [dbo].[Table2] AS [Extent2] ON [Extent1].[Table2ID] = [Extent2].[ID]
WHERE ([Extent1].[TableDate] >= @p__linq__0)',N'@p__linq__0 datetime2(7)',@p__linq__0='0001-01-01 00:00:00'

此外，以下是.edmx的摘录：

<EntityContainer>
      <AssociationSet Name="FK_Table1_Table2" Association="MyModel.Store.FK_Table1_Table2">
        <End Role="Table2" EntitySet="Table2" />
        <End Role="Table1" EntitySet="Table1" />
      </AssociationSet>
</EntityContainer>

<!-- ... -->

<EntityType Name="Table2">
  <Key>
    <PropertyRef Name="ID" />
  </Key>
  <Property Name="ID" Type="int" Nullable="false" />
  <Property Name="SomeString" Type="nvarchar" Nullable="false" MaxLength="50" />
  <Property Name="Table4ID" Type="int" />
</EntityType>

<!-- ... -->

<EntityType Name="Table1">
  <Key>
    <PropertyRef Name="ID" />
  </Key>
  <Property Name="ID" Type="int" Nullable="false" StoreGeneratedPattern="Identity" />
  <Property Name="TableDate" Type="date" Nullable="false" />
  <Property Name="Table2ID" Type="int" Nullable="false" />
</EntityType>

<!-- ... -->

<Association Name="FK_Table1_Table2">
  <End Role="Table2" Type="MyModel.Store.Table2" Multiplicity="1" />
  <End Role="Table1" Type="MyModel.Store.Table1" Multiplicity="*" />
  <ReferentialConstraint>
    <Principal Role="Table2">
      <PropertyRef Name="ID" />
    </Principal>
    <Dependent Role="Table1">
      <PropertyRef Name="Table2ID" />
    </Dependent>
   </ReferentialConstraint>
</Association>

我猜Include（）会导致查询的计算顺序不符合预期，因此调用Where（）时TableDate不可用。如果强制求值，然后调用Where（）

SQL server中的实际数据不一致似乎是个问题。
如前所述

当两个表中至少有一个匹配项时，INNER JOIN关键字返回行。如果“表1”中的行与“表2”中的行不匹配，则不会列出这些行

此查询没有失败的原因，除非“Table2”中确实没有与“Table1”匹配的行。虽然这很奇怪，因为FK约束是强制执行的，但这值得提出另一个问题，并且这个案例已经结束。

有些事情令人信服，因为它需要一个

内部的，而不是左侧的从表1
连接到表2
。你能告诉我们更多关于sql模式的信息吗，或者举一个最小的错误例子吗？请展示你正在使用的映射。我用sql语句编辑了这个问题，以创建上面的表。同时，我将尽量减少出错的例子。数据库中有哪些数据？如果直接在SSMS中执行该查询，会发生什么？内部联接是正确的，因为您有不可为空的FK和多重性1。可以解释缺少PK的原因是，DRI设置不正确，在设置DRI之前插入的记录，使用DRI插入的记录被禁用。检查约束，希望它能找到错误。尝试在SSMS中插入FK无效的记录，并验证其是否失败。禁用FK约束的目的是为了更快地插入。我将其用于一些我（合理地）确信没有违反约束的大型导入，然后启用约束。