为什么生成的查询不同？

Question

我有这样的：

Dim compareAddress1 = (From d In db.Addresses Where d.Address1.Equals("a") And _ 
       d.Address2.Equals(Nothing) And _ 
       d.City.Equals(Nothing) And _ 
       d.POBox.Equals(Nothing) And _ 
       d.PostalCode.Equals(Nothing) And _ 
       d.ZipCode.Equals(Nothing)) 

    Dim compareAddress2 = (From d In db.Addresses Where _ 
        d.Address1.Equals(_address.Address1) And _ 
        d.Address2.Equals(_address.Address2) And _ 
        d.City.Equals(_address.City) And _ 
        d.POBox.Equals(_address.POBox) And _ 
        d.PostalCode.Equals(_address.PostalCode) And _ 
        d.ZipCode.Equals(_address.ZipCode)) 

的对象_address所有领域都为空。

当我使用的对象，我得到这个查询：

SELECT [t0].[AddressID], [t0].[Address1], [t0].[Address2], [t0].[City], [t0].[CountryProvinceID], [t0].[POBox], [t0].[PostalCode], [t0].[ZipCode] 
    FROM [dbo].[Address] AS [t0] 
    WHERE ([t0].[Address1] = @p0) AND ([t0].[Address2] = @p1) AND ([t0].[City] = @p2) AND ([t0].[POBox] = @p3) AND ([t0].[PostalCode] = @p4) AND ([t0].[ZipCode] = @p5) 
    ------------------------------- 
    @p0 [AnsiString]: a 
    @p1 [AnsiString]: 
    @p2 [AnsiString]: 
    @p3 [AnsiString]: 
    @p4 [AnsiString]: 
    @p5 [AnsiString]: 

当我硬编码数据，我得到这个查询：

SELECT [t0].[AddressID], [t0].[Address1], [t0].[Address2], [t0].[City], [t0].[CountryProvinceID], [t0].[POBox], [t0].[PostalCode], [t0].[ZipCode] 
    FROM [dbo].[Address] AS [t0] 
    WHERE ([t0].[Address1] = @p0) AND ([t0].[Address2] IS NULL) AND ([t0].[City] IS NULL) AND ([t0].[POBox] IS NULL) AND ([t0].[PostalCode] IS NULL) AND ([t0].[ZipCode] IS NULL) 
    ------------------------------- 
    @p0 [AnsiString]: a 

人知道为什么吗？以及如何解决我的问题？

Answer 1

Scott Guthrie创建了一个add，它在调试器中起作用。

get it here

Answer 2

怎么样的LINQ to SQL调试展台：

http://weblogs.asp.net/scottgu/archive/2007/07/31/linq-to-sql-debug-visualizer.aspx

Answer 3

给这个一杆...

Dim results = db.Addresses.Where(Function(d) d.Address1.Equals(_address.Address1) And _ 
              d.Address2.Equals(_address.Address2) And _ 
              d.City.Equals(_address.City) And _ 
              d.POBox.Equals(_address.POBox) And _ 
              d.PostalCode.Equals(_address.PostalCode) And _ 
              d.ZipCode.Equals(_address.ZipCode)) 

Console.WriteLine(db.GetCommand(results).CommandText) 

Dim compareAddresses = results.SingleOrDefault() 

Answer 4

你运行针对SQL服务器2002年，我这个LINQ当对sql 2000运行linq时看到了一些奇怪的行为（和你的一样）