如何查看实体框架生成的SQL ?
(在我的特殊情况下,我使用mysql提供商-如果它重要)
如何查看实体框架生成的SQL ?
(在我的特殊情况下,我使用mysql提供商-如果它重要)
当前回答
在EF 4.1中可以执行以下操作:
var result = from x in appEntities
where x.id = 32
select x;
System.Diagnostics.Trace.WriteLine(result .ToString());
这将为您提供生成的SQL。
其他回答
对于那些使用Entity Framework 6及以上版本的用户,如果你想在Visual Studio中查看输出SQL(就像我做的那样),你必须使用新的日志/拦截功能。
添加下面这行代码将在Visual Studio输出面板中输出生成的SQL(以及其他与执行相关的详细信息):
using (MyDatabaseEntities context = new MyDatabaseEntities())
{
context.Database.Log = s => System.Diagnostics.Debug.WriteLine(s);
// query the database using EF here.
}
有关登录EF6的更多信息,请参阅这个漂亮的博客系列:http://blog.oneunicorn.com/2013/05/08/ef6-sql-logging-part-1-simple-logging/
注意:确保在DEBUG模式下运行项目。
从实体框架核心5.0+开始,可以简单地覆盖DbContext中的onconfiguration方法一次用于日志记录。这也适用于Single()或Any()查询。
日志记录到调试窗口:
public class ExampleDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
// using System.Diagnostics;
optionsBuilder.LogTo(message => Debug.WriteLine(message));
}
}
登录控制台:
public class ExampleDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.LogTo(Console.WriteLine);
}
}
更多详细信息,包括日志级别和过滤:https://learn.microsoft.com/en-us/ef/core/logging-events-diagnostics/simple-logging
在我的EF 6+的情况下,而不是在立即窗口中使用这个来查找查询字符串:
var sql = ((System.Data.Entity.Core.Objects.ObjectQuery)query).ToTraceString();
我最终不得不使用这个来获得生成的SQL命令:
var sql = ((System.Data.Entity.Infrastructure.DbQuery<<>f__AnonymousType3<string,string,string,short,string>>)query).ToString();
当然,您的匿名类型签名可能有所不同。
HTH.
有两种方法:
To view the SQL that will be generated, simply call ToTraceString(). You can add it into your watch window and set a breakpoint to see what the query would be at any given point for any LINQ query. You can attach a tracer to your SQL server of choice, which will show you the final query in all its gory detail. In the case of MySQL, the easiest way to trace the queries is simply to tail the query log with tail -f. You can learn more about MySQL's logging facilities in the official documentation. For SQL Server, the easiest way is to use the included SQL Server profiler.
虽然这里有很好的答案,但没有一个完全解决了我的问题(我希望从任何IQueryable DbContext中获得整个SQL语句,包括参数)。下面的代码就是这样做的。它是来自谷歌的代码片段的组合。我只用EF6+测试过。
说句题外话,这项任务花的时间比我想象的要长得多。恕我直言,实体框架中的抽象有点太多了。
首先是使用。您需要显式引用'System.Data.Entity.dll'。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.SqlClient;
using System.Data.Common;
using System.Data.Entity.Core.Objects;
using System.Data.Entity;
using System.Data;
using System.Data.Entity.Infrastructure;
using System.Reflection;
下面的类将一个IQueryable转换为一个DataTable。根据您的需要修改:
public class EntityFrameworkCommand
{
DbContext Context;
string SQL;
ObjectParameter[] Parameters;
public EntityFrameworkCommand Initialize<T>(DbContext context, IQueryable<T> query)
{
Context = context;
var dbQuery = query as DbQuery<T>;
// get the IInternalQuery internal variable from the DbQuery object
var iqProp = dbQuery.GetType().GetProperty("InternalQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
var iq = iqProp.GetValue(dbQuery, null);
// get the ObjectQuery internal variable from the IInternalQuery object
var oqProp = iq.GetType().GetProperty("ObjectQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
var objectQuery = oqProp.GetValue(iq, null) as ObjectQuery<T>;
SQL = objectQuery.ToTraceString();
Parameters = objectQuery.Parameters.ToArray();
return this;
}
public DataTable GetData()
{
DataTable dt = new DataTable();
var connection = Context.Database.Connection;
var state = connection.State;
if (!(state == ConnectionState.Open))
connection.Open();
using (var cmd = connection.CreateCommand())
{
cmd.CommandText = SQL;
foreach (var p in Parameters)
{
var param = cmd.CreateParameter();
param.Name = "@" + p.Name;
param.Value = p.Value;
cmd.Parameters.Add(param);
}
using (var da = DbProviderFactories.GetFactory(connection).CreateDataAdapter())
{
da.SelectCommand = cmd;
da.Fill(dt);
}
}
if (!(state == ConnectionState.Open))
connection.Close();
return dt;
}
}
要使用,只需如下所示调用它:
var context = new MyContext();
var data = ....//Query, return type can be anonymous
.AsQueryable();
var dt = new EntityFrameworkCommand()
.Initialize(context, data)
.GetData();