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C# 有趣的Linq到SQL通用基类行为

c# linq-to-sql

C# 有趣的Linq到SQL通用基类行为,c#,linq-to-sql,cil,C#,Linq To Sql,Cil,这是一个关于InvalidOperationException的问题，消息类成员X未映射 对于框架版本为3.5的每个LinqToSql实体，我们的一个系统具有相同的基本实体 我遇到了一个非常奇怪的问题，我开始研究它。我做了一个非常小的项目，以便能够更容易地定位问题 实体基类 public abstract class EntityBase { public virtual long ID { get; set; } } .method public hidebysig instance

这是一个关于InvalidOperationException的问题，消息类成员X未映射

对于框架版本为3.5的每个LinqToSql实体，我们的一个系统具有相同的基本实体

我遇到了一个非常奇怪的问题，我开始研究它。我做了一个非常小的项目，以便能够更容易地定位问题

实体基类

public abstract class EntityBase
{
    public virtual long ID { get; set; }
}

.method public hidebysig instance void WithEquals(class LinqToSqlTest.EntitiesDataContext ctx) cil managed
    {
        .maxstack 7
        .locals init (
            [0] class [System.Core]System.Linq.Expressions.ParameterExpression CS$0$0000,
            [1] class [System.Core]System.Linq.Expressions.Expression[] CS$0$0001,
            [2] class [System.Core]System.Linq.Expressions.ParameterExpression[] CS$0$0002)
        L_0000: nop 
        L_0001: ldarg.1 
        L_0002: callvirt instance class [System.Data.Linq]System.Data.Linq.Table`1<!!0> [System.Data.Linq]System.Data.Linq.DataContext::GetTable<class LinqToSqlTest.MyEntity>()
        L_0007: ldtoken LinqToSqlTest.MyEntity
        L_000c: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0011: ldstr "i"
        L_0016: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_001b: stloc.0 
        L_001c: ldloc.0 
        L_001d: ldtoken instance int64 LinqToSqlTest.EntityBase::get_ID()
        L_0022: call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle(valuetype [mscorlib]System.RuntimeMethodHandle)
        L_0027: castclass [mscorlib]System.Reflection.MethodInfo
        L_002c: call class [System.Core]System.Linq.Expressions.MemberExpression [System.Core]System.Linq.Expressions.Expression::Property(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo)
        L_0031: ldtoken instance bool [mscorlib]System.Int64::Equals(int64)
        L_0036: call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle(valuetype [mscorlib]System.RuntimeMethodHandle)
        L_003b: castclass [mscorlib]System.Reflection.MethodInfo
        L_0040: ldc.i4.1 
        L_0041: newarr [System.Core]System.Linq.Expressions.Expression
        L_0046: stloc.1 
        L_0047: ldloc.1 
        L_0048: ldc.i4.0 
        L_0049: ldc.i4.2 
        L_004a: conv.i8 
        L_004b: box int64
        L_0050: ldtoken int64
        L_0055: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_005a: call class [System.Core]System.Linq.Expressions.ConstantExpression [System.Core]System.Linq.Expressions.Expression::Constant(object, class [mscorlib]System.Type)
        L_005f: stelem.ref 
        L_0060: ldloc.1 
        L_0061: call class [System.Core]System.Linq.Expressions.MethodCallExpression [System.Core]System.Linq.Expressions.Expression::Call(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo, class [System.Core]System.Linq.Expressions.Expression[])
        L_0066: ldc.i4.1 
        L_0067: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_006c: stloc.2 
        L_006d: ldloc.2 
        L_006e: ldc.i4.0 
        L_006f: ldloc.0 
        L_0070: stelem.ref 
        L_0071: ldloc.2 
        L_0072: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, bool>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_0077: call !!0 [System.Core]System.Linq.Queryable::FirstOrDefault<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, bool>>)
        L_007c: pop 
        L_007d: ret 
    }
数据上下文和实体

[Database(Name = "TestDatabase")]
public class EntitiesDataContext : DataContext
{
    public EntitiesDataContext() :
        base(Settings.Default.TestDatabaseConnectionString, new AttributeMappingSource())
    {
    }
}

[Table(Name = "dbo.MyEntity")]
public class MyEntity : EntityBase
{
    private long _EntityID;

    [Column(Name = "EntityID", Storage = "_EntityID")]
    public override long ID
    {
        get { return _EntityID; }
        set { _EntityID = value; }
    }

    [Column] public string Title;
}
问题是被覆盖的ID。我对不同的映射属性/属性名称设置做了很多修改，但问题似乎不是命名，而是基类。而且.NET3.5和.NET4.0之间也有区别

因此，对于下面的语句，想象一个

using (var ctx = new EntitiesDataContext())
{
    //statement
}
周围

GetTable（）是
GetTable（）。

失败表示类成员EntityBase.ID未映射。例外有效表示预期行为

1（在3.5中）工程：

2（在3.5中）失败：

var result = ctx.GetTable().FirstOrDefault(i => i.ID == 2);
var result = ctx.GetTable().Where(i => i.ID == 2).FirstOrDefault()
public void WithEquals(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID.Equals(2));
}

public void WithFakeWhereAndOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => true).FirstOrDefault(i => i.ID == 2);
}

public void WithOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID == 2);
}

public void WithOperatorSelect(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).Select(i => i).FirstOrDefault();
}

public void WithOperatorAndWhere(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).FirstOrDefault();
}
3（在3.5中）工程：

4（在3.5中）工程：

5（在3.5中）工程：

6（在4.0中）失败：

var result = ctx.GetTable().FirstOrDefault(i => i.ID == 2);
var result = ctx.GetTable().Where(i => i.ID == 2).FirstOrDefault()
public void WithEquals(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID.Equals(2));
}

public void WithFakeWhereAndOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => true).FirstOrDefault(i => i.ID == 2);
}

public void WithOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID == 2);
}

public void WithOperatorSelect(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).Select(i => i).FirstOrDefault();
}

public void WithOperatorAndWhere(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).FirstOrDefault();
}
7（在4.0中）工程：

8（在4.0中）失败（与6冗余）

9（在4.0中）工程：

10（在4.0中）工程：

So 我不明白为什么它在失败的地方失败。特别是，为什么这样做有效

var result = ctx.GetTable().Where(i => true).FirstOrDefault(i => i.ID == 2);
如果带谓词的FirstOrDefault不存在？以及为什么在==不存在的情况下，Equals起作用

我一直在寻找一些Equals和==差异描述，但它没有给我在哪里的答案（I=>true）。。。事情

似乎不是关于查询，而是关于对象初始化。因为：

在4.0版本中：

var result = ctx.GetTable().Where(i => i.ID.Equals(2)).FirstOrDefault();
var result = ctx.GetTable().FirstOrDefault(i => i.ID.Equals(2));
ctx.GetTable().Where(i => true).FirstOrDefault(i => i.ID == 2);
var result = ctx.GetTable().Where(i => i.ID == 2).Select(i => i.Title).FirstOrDefault();
但是：）

在4.0中，它还可以工作：

var result = ctx.GetTable().FirstOrDefault();
所以可能不是对象初始化

LinqToSql正在构建的SQL与==和等于的相同。同样，对于

Where(i => true).FirstOrDefault(i => i.ID == 2)
及

在FirstOrDefault之前没有SQL查询，并且它按照预期正确地构建了查询。其中（i=>true）只是继续SQL查询中包含的表达式构建和FirstOrDefault谓词

我在MSIL的Reflector中查找其他原因，但没有发现任何特别的原因

猜猜看？：）

多谢各位

#####延续（在.NET4.0中）

我设置了5种简单的方法来轻松地检入反射器：

var result = ctx.GetTable().FirstOrDefault(i => i.ID == 2);
var result = ctx.GetTable().Where(i => i.ID == 2).FirstOrDefault()
public void WithEquals(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID.Equals(2));
}

public void WithFakeWhereAndOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => true).FirstOrDefault(i => i.ID == 2);
}

public void WithOperator(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().FirstOrDefault(i => i.ID == 2);
}

public void WithOperatorSelect(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).Select(i => i).FirstOrDefault();
}

public void WithOperatorAndWhere(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).FirstOrDefault();
}

初始化，它在方法的中间调用相等。

另外，我可以看到with operator使用

call class [System.Core]System.Linq.Expressions.BinaryExpression [System.Core]System.Linq.Expressions.Expression::Equal(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.Expression)
而with equals使用

call class [System.Core]System.Linq.Expressions.MethodCallExpression [System.Core]System.Linq.Expressions.Expression::Call(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo, class [System.Core]System.Linq.Expressions.Expression[])
这在第二张图像的第38行中

嗯，也许这是关于二进制表达式和方法调用表达式之间的区别的问题？我将对此做进一步的研究

依此类推

我们有一个工作小组

public void WithOperatorSelect(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).Select(i => i).FirstOrDefault();
}

public void with operator select（EntitiesDataContext ctx）
{
GetTable（）.Where（i=>i.ID==2）.Select（i=>i.FirstOrDefault（）；
}
同

public void WithOperatorAndWhere(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).FirstOrDefault();
}

public void with operator and where（EntitiesDataContext ctx）
{
GetTable（）.Where（i=>i.ID==2.FirstOrDefault（）；
}
但是通过一个额外的假选择，它就可以工作了

MSIL

使用运算符并选择

.method public hidebysig instance void WithOperatorSelect(class LinqToSqlTest.EntitiesDataContext ctx) cil managed
    {
        .maxstack 5
        .locals init (
            [0] class [System.Core]System.Linq.Expressions.ParameterExpression CS$0$0000,
            [1] class [System.Core]System.Linq.Expressions.ParameterExpression[] CS$0$0001)
        L_0000: nop 
        L_0001: ldarg.1 
        L_0002: callvirt instance class [System.Data.Linq]System.Data.Linq.Table`1<!!0> [System.Data.Linq]System.Data.Linq.DataContext::GetTable<class LinqToSqlTest.MyEntity>()
        L_0007: ldtoken LinqToSqlTest.MyEntity
        L_000c: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0011: ldstr "i"
        L_0016: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_001b: stloc.0 
        L_001c: ldloc.0 
        L_001d: ldtoken instance int64 LinqToSqlTest.EntityBase::get_ID()
        L_0022: call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle(valuetype [mscorlib]System.RuntimeMethodHandle)
        L_0027: castclass [mscorlib]System.Reflection.MethodInfo
        L_002c: call class [System.Core]System.Linq.Expressions.MemberExpression [System.Core]System.Linq.Expressions.Expression::Property(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo)
        L_0031: ldc.i4.2 
        L_0032: conv.i8 
        L_0033: box int64
        L_0038: ldtoken int64
        L_003d: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0042: call class [System.Core]System.Linq.Expressions.ConstantExpression [System.Core]System.Linq.Expressions.Expression::Constant(object, class [mscorlib]System.Type)
        L_0047: call class [System.Core]System.Linq.Expressions.BinaryExpression [System.Core]System.Linq.Expressions.Expression::Equal(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.Expression)
        L_004c: ldc.i4.1 
        L_004d: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_0052: stloc.1 
        L_0053: ldloc.1 
        L_0054: ldc.i4.0 
        L_0055: ldloc.0 
        L_0056: stelem.ref 
        L_0057: ldloc.1 
        L_0058: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, bool>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_005d: call class [System.Core]System.Linq.IQueryable`1<!!0> [System.Core]System.Linq.Queryable::Where<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, bool>>)
        L_0062: ldtoken LinqToSqlTest.MyEntity
        L_0067: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_006c: ldstr "i"
        L_0071: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_0076: stloc.0 
        L_0077: ldloc.0 
        L_0078: ldc.i4.1 
        L_0079: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_007e: stloc.1 
        L_007f: ldloc.1 
        L_0080: ldc.i4.0 
        L_0081: ldloc.0 
        L_0082: stelem.ref 
        L_0083: ldloc.1 
        L_0084: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, class LinqToSqlTest.MyEntity>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_0089: call class [System.Core]System.Linq.IQueryable`1<!!1> [System.Core]System.Linq.Queryable::Select<class LinqToSqlTest.MyEntity, class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, !!1>>)
        L_008e: call !!0 [System.Core]System.Linq.Queryable::FirstOrDefault<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>)
        L_0093: pop 
        L_0094: ret 
    }

.method public hidebysing实例void with operator select（类LinqToSqlTest.EntitiesDataContext ctx）cil managed
{
.maxstack 5
.init(
[0]类[System.Core]System.Linq.Expressions.ParameterExpression CS$0$0000，
[1] 类[System.Core]System.Linq.Expressions.ParameterExpression[]CS$0$0001）
L_0000：没有
L_0001:ldarg.1
L_0002:callvirt实例类[System.Data.Linq]System.Data.Linq.Table`1[System.Data.Linq]System.Data.Linq.DataContext:：GetTable（）
L_0007:ldtoken LinqToSqlTest.MyEntity
L_000c:call class[mscorlib]System.Type[mscorlib]System.Type:：GetTypeFromHandle（valuetype[mscorlib]System.RuntimeTypeHandle）
L_0011:ldstr“i”
L_0016:调用类[System.Core]System.Linq.Expressions.ParameterExpression[System.Core]System.Linq.Expressions.Expression:：Parameter（类[mscorlib]System.Type，字符串）
L_001b:stloc.0
L_001c:ldloc.0
L_001d:ldtoken实例int64 LinqToSqlTest.EntityBase:：get_ID（）
L_0022:调用类[mscorlib]System.Reflection.MethodBase[mscorlib]System.Reflection.MethodBase:：GetMethodFromHandle（valuetype[mscorlib]System.RuntimeMethodHandle）
L_0027:castclass[mscorlib]System.Reflection.MethodInfo
L_002c:调用类[System.Core]System.Linq.Expressions.MemberExpression[System.Core]System.Linq.Expressions.Expression:：Property（类[System.Core]System.Linq.Expressions.Expression，类[mscorlib]System.Reflection.MethodInfo）
L_0031:ldc.i4.2
L_0032:conv.i8
L_0033:box int64
L_0038:ldtoken int64
L_003d:调用类[mscorlib]System.Type[mscorlib]System.Type:：GetTypeFromHandle（valuetype[mscorlib]System.RuntimeTypeHandle）
L_0042:调用类[System.Core]System.Linq.Expressions.ConstantExpression[System.Core]System.Linq.Expressions.Expression:：Constant（对象，类[mscorlib]System.Type）
L_0047:调用类[System.Core]System.Linq.Expressions.BinaryExpression[System.Core]System.Linq.Expressions.Expression:：Equal（类[System.Core]System.Linq.Expressions.Expression，类[System.Core]System.Linq.Expressions.Expression）
L_004c:ldc.i4.1
L_004d:newarr[System.Core]System.Linq.Expressions.ParameterExpression
L_0052:stloc.1
L_0053:ldloc.1
L_0054:ldc.i4.0
L_0055:ldloc.0
L_0056:stelem.ref
L_0057:ldloc.1
L_0058:调用类[Sys]

public void WithOperatorSelect(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).Select(i => i).FirstOrDefault();
}



public void WithOperatorAndWhere(EntitiesDataContext ctx)
{
    ctx.GetTable<MyEntity>().Where(i => i.ID == 2).FirstOrDefault();
}



.method public hidebysig instance void WithOperatorSelect(class LinqToSqlTest.EntitiesDataContext ctx) cil managed
    {
        .maxstack 5
        .locals init (
            [0] class [System.Core]System.Linq.Expressions.ParameterExpression CS$0$0000,
            [1] class [System.Core]System.Linq.Expressions.ParameterExpression[] CS$0$0001)
        L_0000: nop 
        L_0001: ldarg.1 
        L_0002: callvirt instance class [System.Data.Linq]System.Data.Linq.Table`1<!!0> [System.Data.Linq]System.Data.Linq.DataContext::GetTable<class LinqToSqlTest.MyEntity>()
        L_0007: ldtoken LinqToSqlTest.MyEntity
        L_000c: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0011: ldstr "i"
        L_0016: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_001b: stloc.0 
        L_001c: ldloc.0 
        L_001d: ldtoken instance int64 LinqToSqlTest.EntityBase::get_ID()
        L_0022: call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle(valuetype [mscorlib]System.RuntimeMethodHandle)
        L_0027: castclass [mscorlib]System.Reflection.MethodInfo
        L_002c: call class [System.Core]System.Linq.Expressions.MemberExpression [System.Core]System.Linq.Expressions.Expression::Property(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo)
        L_0031: ldc.i4.2 
        L_0032: conv.i8 
        L_0033: box int64
        L_0038: ldtoken int64
        L_003d: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0042: call class [System.Core]System.Linq.Expressions.ConstantExpression [System.Core]System.Linq.Expressions.Expression::Constant(object, class [mscorlib]System.Type)
        L_0047: call class [System.Core]System.Linq.Expressions.BinaryExpression [System.Core]System.Linq.Expressions.Expression::Equal(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.Expression)
        L_004c: ldc.i4.1 
        L_004d: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_0052: stloc.1 
        L_0053: ldloc.1 
        L_0054: ldc.i4.0 
        L_0055: ldloc.0 
        L_0056: stelem.ref 
        L_0057: ldloc.1 
        L_0058: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, bool>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_005d: call class [System.Core]System.Linq.IQueryable`1<!!0> [System.Core]System.Linq.Queryable::Where<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, bool>>)
        L_0062: ldtoken LinqToSqlTest.MyEntity
        L_0067: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_006c: ldstr "i"
        L_0071: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_0076: stloc.0 
        L_0077: ldloc.0 
        L_0078: ldc.i4.1 
        L_0079: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_007e: stloc.1 
        L_007f: ldloc.1 
        L_0080: ldc.i4.0 
        L_0081: ldloc.0 
        L_0082: stelem.ref 
        L_0083: ldloc.1 
        L_0084: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, class LinqToSqlTest.MyEntity>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_0089: call class [System.Core]System.Linq.IQueryable`1<!!1> [System.Core]System.Linq.Queryable::Select<class LinqToSqlTest.MyEntity, class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, !!1>>)
        L_008e: call !!0 [System.Core]System.Linq.Queryable::FirstOrDefault<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>)
        L_0093: pop 
        L_0094: ret 
    }



 .method public hidebysig instance void WithOperatorAndWhere(class LinqToSqlTest.EntitiesDataContext ctx) cil managed
    {
        .maxstack 5
        .locals init (
            [0] class [System.Core]System.Linq.Expressions.ParameterExpression CS$0$0000,
            [1] class [System.Core]System.Linq.Expressions.ParameterExpression[] CS$0$0001)
        L_0000: nop 
        L_0001: ldarg.1 
        L_0002: callvirt instance class [System.Data.Linq]System.Data.Linq.Table`1<!!0> [System.Data.Linq]System.Data.Linq.DataContext::GetTable<class LinqToSqlTest.MyEntity>()
        L_0007: ldtoken LinqToSqlTest.MyEntity
        L_000c: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0011: ldstr "i"
        L_0016: call class [System.Core]System.Linq.Expressions.ParameterExpression [System.Core]System.Linq.Expressions.Expression::Parameter(class [mscorlib]System.Type, string)
        L_001b: stloc.0 
        L_001c: ldloc.0 
        L_001d: ldtoken instance int64 LinqToSqlTest.EntityBase::get_ID()
        L_0022: call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle(valuetype [mscorlib]System.RuntimeMethodHandle)
        L_0027: castclass [mscorlib]System.Reflection.MethodInfo
        L_002c: call class [System.Core]System.Linq.Expressions.MemberExpression [System.Core]System.Linq.Expressions.Expression::Property(class [System.Core]System.Linq.Expressions.Expression, class [mscorlib]System.Reflection.MethodInfo)
        L_0031: ldc.i4.2 
        L_0032: conv.i8 
        L_0033: box int64
        L_0038: ldtoken int64
        L_003d: call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle(valuetype [mscorlib]System.RuntimeTypeHandle)
        L_0042: call class [System.Core]System.Linq.Expressions.ConstantExpression [System.Core]System.Linq.Expressions.Expression::Constant(object, class [mscorlib]System.Type)
        L_0047: call class [System.Core]System.Linq.Expressions.BinaryExpression [System.Core]System.Linq.Expressions.Expression::Equal(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.Expression)
        L_004c: ldc.i4.1 
        L_004d: newarr [System.Core]System.Linq.Expressions.ParameterExpression
        L_0052: stloc.1 
        L_0053: ldloc.1 
        L_0054: ldc.i4.0 
        L_0055: ldloc.0 
        L_0056: stelem.ref 
        L_0057: ldloc.1 
        L_0058: call class [System.Core]System.Linq.Expressions.Expression`1<!!0> [System.Core]System.Linq.Expressions.Expression::Lambda<class [mscorlib]System.Func`2<class LinqToSqlTest.MyEntity, bool>>(class [System.Core]System.Linq.Expressions.Expression, class [System.Core]System.Linq.Expressions.ParameterExpression[])
        L_005d: call class [System.Core]System.Linq.IQueryable`1<!!0> [System.Core]System.Linq.Queryable::Where<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>, class [System.Core]System.Linq.Expressions.Expression`1<class [mscorlib]System.Func`2<!!0, bool>>)
        L_0062: call !!0 [System.Core]System.Linq.Queryable::FirstOrDefault<class LinqToSqlTest.MyEntity>(class [System.Core]System.Linq.IQueryable`1<!!0>)
        L_0067: pop 
        L_0068: ret 
    }



object x = 10;
object y = 10;

x == y      // returns false as == is static and the compiler statically binds it
            // to object, which uses a reference comparison, hence the false

x.Equals(y) // returns true as .Equals is virtual, thus calls the Int32 
            // implementation of .Equals which does a value type compare.