EF查询生成的SQL

在EF 4和EF 3.5 SP1中，我们可以使用ToTraceString()方法得到EF查询所生成的SQL。

 1 using (var context = new TestDBEntities())
 2 {
 3     var query = from p in context.Parents
 4                 where p.Name == "zhaokun"
 5                 select p;
 6 
 7     ObjectQuery<Parent> parents = query as ObjectQuery<Parent>;
 8     if (parents != null)
 9     {
10         string sql = parents.ToTraceString();
11     }
12 }

totracestring

这里所生成的SQL为：

1 [Extent1].[ParentID] AS [ParentID], 
2 [Extent1].[Name] AS [Name]
3 FROM [dbo].[Parent] AS [Extent1]
4 WHERE N'zhaokun'=[Extent1].[Name]

sqlone

在EF 4.1中，我们可以直接调用DbQuery<>的ToString()方法得到所生成的SQL。

1 using (var context = new MyDbContext())
2 {
3     var people = from p in context.People
4                  where p.PersonID > 100
5                  select p;
6 
7     string sql = people.ToString();
8 }

tostring

所生成的SQL是：

1 SELECT 
2 [Extent1].[PersonID] AS [PersonID], 
3 [Extent1].[Name] AS [Name]
4 FROM [dbo].[People] AS [Extent1]
5 WHERE [Extent1].[PersonID] > 100

sqltwo

这里的ToString()方法其实也就是调用了ObjectQuery<>的ToTraceString()方法。 DbQuery<>.ToString() ==> System.Data.Entity.Internal.Linq.InternalQuery<>.ToString()方法，此方法在.NET Reflector得到的实现是这样的：

1 public override string ToString()
2 {
3     return this._objectQuery.ToTraceString();
4 }

tostring（）

看书得到！