查看LINQ生成SQL语句的几种方法

记录LINQ生成的SQL语句是常用的调试方式,而且能根据需要来优化LINQ生成的SQL语句,更能了深入的了解LINQ.

DataContext的Log属性来将LINQ to SQL生成的SQL语句格式化.

一.控制台程序(Console)

dataContext.Log = Console.Out;

二.利用GetCommand方法

dataContext.GetCommand(query).CommandText;

三.使用LINQPad (官方网站)

LINQPad支持C# 3.0 和 Framework 3.5的全部功能：
LINQ to SQL
LINQ to Objects
LINQ to XML

 

更多介绍请参考李永京的学习LINQ工具：LINQPad

下载地址:http://www.albahari.com/LINQPad.exe

四.LINQ to SQL Debug Visualizer

ScottGu的LINQ to SQL Debug Visualizer可以在Debug过程中查看SQL语句.

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

下载:http://www.scottgu.com/blogposts/linqquery/SqlServerQueryVisualizer.zip

安装方法

1. 关闭 VS2008。

2. 将压缩包中的 SqlServerQueryVisualizer.dll 拷贝到 \Program Files\Microsoft Visual Studio 9.0\Common7\Packages\Debugger\Visualizers。

3. 重启 VS2008 即可。

五.DebuggerWriter工具类

由于Console.Out方法在ASP.NET程序不起作用.

Kris Vandermotten 已经创建好了一个这个工具类, 你只要使用这样的语法:

MyDataContext db = new MyDataContext();

db.Log = new DebuggerWriter();

asp.net可以选择将Log信息直接发送到Debug的输出窗口.

源码:

using System;


using System.Diagnostics;


using System.Globalization;


using System.IO;


using System.Text;




namespace Vandermotten.Diagnostics


{


    /// <summary>


    /// Implements a <see cref="TextWriter"/> for writing information to the debugger log.


    /// </summary>


    /// <seealso cref="Debugger.Log"/>


    public class DebuggerWriter : TextWriter


    {


        private bool isOpen;


        private static UnicodeEncoding encoding;


        private readonly int level;


        private readonly string category;




        /// <summary>


        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class.


        /// </summary>


        public DebuggerWriter()


            : this(0, Debugger.DefaultCategory)


        {


        }




        /// <summary>


        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class with the specified level and category.


        /// </summary>


        /// <param name="level">A description of the importance of the messages.</param>


        /// <param name="category">The category of the messages.</param>


        public DebuggerWriter(int level, string category)


            : this(level, category, CultureInfo.CurrentCulture)


        {


        }




        /// <summary>


        /// Initializes a new instance of the <see cref="DebuggerWriter"/> class with the specified level, category and format provider.


        /// </summary>


        /// <param name="level">A description of the importance of the messages.</param>


        /// <param name="category">The category of the messages.</param>


        /// <param name="formatProvider">An <see cref="IFormatProvider"/> object that controls formatting.</param>


        public DebuggerWriter(int level, string category, IFormatProvider formatProvider)


            : base(formatProvider)


        {


            this.level = level;


            this.category = category;


            this.isOpen = true;


        }




        protected override void Dispose(bool disposing)


        {


            isOpen = false;


            base.Dispose(disposing);


        }




        public override void Write(char value)


        {


            if (!isOpen)


            {


                throw new ObjectDisposedException(null);


            }


            Debugger.Log(level, category, value.ToString());


        }




        public override void Write(string value)


        {


            if (!isOpen)


            {


                throw new ObjectDisposedException(null);


            }


            if (value != null)


            {


                Debugger.Log(level, category, value);


            }


        }




        public override void Write(char[] buffer, int index, int count)


        {


            if (!isOpen)


            {


                throw new ObjectDisposedException(null);


            }


            if (buffer == null || index < 0 || count < 0 || buffer.Length - index < count)


            {


                base.Write(buffer, index, count); // delegate throw exception to base class


            }


            Debugger.Log(level, category, new string(buffer, index, count));


        }




        public override Encoding Encoding


        {


            get


            {


                if (encoding == null)


                {


                    encoding = new UnicodeEncoding(false, false);


                }


                return encoding;


            }


        }




        public int Level


        {


            get { return level; }


        }




        public string Category


        {


            get { return category; }


        }


    }


}



六.将LINQ to SQL生成的SQL语句写入日志文件

DataContext.Log是System.IO.TextWriter类型,所以你可以用以下的方法来做.

StreamWriter sw = new StreamWriter(
Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "log.txt"));

dBLinqDataContext.Log = sw;

var query = dataContext.Customers.Single<Customer>(c=>c.CustomerID.Contains("s"))
.Skip(0).Take(10).ToList();

sw.Flush();

sw.Close();

但以上方法有个缺点,就是需要在每个实现的方法中都写这么多代码.使用起来太不方便.参照dataContext.Log = Console.Out的表现形式

由是有了FileLog类.(当然,FileLog类除了此功能还有一些基本的记录日志的方法)

使用时直接dataContext.Log = Yaosansi.IO.FileLog.Out;即可. 默认会在桌面上生成一个名叫UnNameFile.txt的文件.

当然如果你不想使用默认的文件名和路径也可以使用dataContext.Log =new Yaosansi.IO.FileLog("FileName")的方式.

下面是FileLog类的源码:


//原文:http://www.yaosansi.com/post/1380.html


using System;


using System.Collections.Generic;


using System.Text;


using System.IO;




namespace Yaosansi.IO


{


    /// <summary>


    /// 文件操作


    /// </summary>


    public class FileLog : TextWriter


    {


        #region 构造函数




      


        /// <summary>


        /// 


        /// </summary>


        /// <param name="fileName">文件名[文件路径使用默认路径]</param>


        public FileLog(string fileName)


            : this(fileName,string.Empty,false)


        {


        }




        /// <summary>


        /// 


        /// </summary>


        /// <param name="fileName">文件名</param>


        /// <param name="filePath">文件路径</param>


        /// <param name="deleteExistingFile">是否删除已经存在的文件</param>


        public FileLog(string fileName,string filePath, bool deleteExistingFile):this(fileName,filePath,long.MaxValue)


        {


            if (deleteExistingFile)


            {


                DeleteFile();


            }


        }




        /// <summary>


        /// 


        /// </summary>


        /// <param name="fileName">文件名</param>


        /// <param name="filePath">文件路径</param>


        /// <param name="fileSize">文件大小［单位：bytes］超出此大小将自动删除文件(使用longong.MaxValue例外)</param>


        /// 


        public FileLog(string fileName, string filePath, long fileSize)


        {


            if (!string.IsNullOrEmpty(fileName))


            {


                FileName = fileName;


            }


            else


            {


                FileName = "UnNameFile.txt";


            }


            if (!string.IsNullOrEmpty(filePath))


            {


                FilePath = filePath;


            }


            else


            {


                FilePath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);


            }


            FileSize = fileSize;


        }


        #endregion




        #region 重写TextWriter






        public override Encoding Encoding


        {


            get


            {


                return new UnicodeEncoding(false, false);


            }


        }






        public override void Write(char value)


        {


            WriteFile(value.ToString());


        }




        public override void Write(string value)


        {


            if (value != null)


            {


                WriteFile(value);


            }


        }




        public override void Write(char[] buffer, int index, int count)


        {


            if (buffer == null || index < 0 || count < 0 || buffer.Length - index < count)


            {


                base.Write(buffer, index, count);


            }


            WriteFile(new string(buffer, index, count));


        }




        #endregion




        #region 属性


        /// <summary>


        /// 文件名


        /// </summary>


        public string FileName { set; get; }




        /// <summary>


        /// 获取文件全名［包含路径］


        /// </summary>


        public string FullFileName


        {


            get


            {


                return FilePath + "\\" + FileName;


            }


        }




        /// <summary>


        /// 定义文件大小


        /// </summary>




        public long FileSize { set; get; }




        /// <summary>


        /// 文件路径;


        /// </summary>




        public string FilePath


        {


            set;


            get;


        }




        /// <summary>


        /// FileLog Factory


        /// </summary>


        public static FileLog Out


        {


            get


            {


                return new FileLog("");


            }


        }




        #endregion




        #region 方法


        /// <summary>


        /// 删除文件


        /// </summary>


        /// <returns></returns>


        public bool DeleteFile()


        {


            bool succeed = false;


            try


            {


                if (File.Exists(FullFileName))


                {


                    File.Delete(FullFileName);


                    succeed = true;


                }


            }


            catch { }


            return succeed;


        }






        /// <summary>


        /// 仅记录当前时间及分隔符


        /// </summary>


        public void WirteTime()


        {


            string message = "\r\n-------------------------------------------------------\r\n" +


                            "时间:" + DateTime.Now.ToString() + "\r\n" +


                            "-------------------------------------------------------";


            WriteFile(message);


        }




        /// <summary>


        /// 写文件


        /// </summary>


        /// <param name="Message"></param>


        public void WriteFile(string Message)


        {


            StreamWriter sw = null;


            try


            {


                //如果文件目录不存在,则创建


                if (!Directory.Exists(FilePath))


                {


                    Directory.CreateDirectory(FilePath);


                }


                //超过一定大小自动删除文件


                if (FileSize != long.MaxValue)


                {


                    FileInfo finfo = new FileInfo(FullFileName);


                    if (finfo.Exists && finfo.Length > FileSize)


                    {


                        finfo.Delete();


                    }


                }


                if (!File.Exists(FullFileName))


                {


                    sw = File.CreateText(FullFileName);


                }


                else


                {


                    sw = File.AppendText(FullFileName);


                }


                sw.WriteLine(Message);


                sw.Flush();


            }


            catch (Exception ee)


            {


                Console.WriteLine("文件没有打开,详细信息如下:" + ee.ToString());


                throw (new Exception("文件没有打开,详细信息如下:" + ee.ToString()));


            }


            finally


            {


                sw.Close();


                sw.Dispose();


            }


        }


        #endregion






    }


}