用T4模版生成对应数据库表的实体类

 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ output extension=".cs" #>
 <#@ assembly name="System.Data" #>
 <#@ assembly name="System.Xml" #>
 <#@ import namespace="System" #>
 <#@ import namespace="System.Xml" #>
 <#@ import namespace="System.Data" #>
 <#@ import namespace="System.Data.SqlClient" #>
 <#
 ModelManager manager = new ModelManager();
 string tableName = "tbOptAuthor";
 DataTable table= manager.GetTableSchema(tableName);
 #>
 /* ****************************************************************************************
  * 版权所有：西安xxx软件有限公司
  * 用    途：数据传输对象(DTO)
  * 结构组成：
  * 作    者：xxx
  * 创建日期：<#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#>
  * 历史记录：
  * ****************************************************************************************
  * 修改人员：
  * 修改日期：
  * 修改说明：
  * ****************************************************************************************/
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;

 namespace wgx.Model
 {
     [Serializable]
     /// <summary>
     /// <#= tableName.Replace("tb","DTO_") #>
     /// </summary>
     public class <#= tableName.Replace("tb","DTO_") #>
     {
         #region 属性
     <#
     foreach(DataRow row in table.Rows)
     {
     #>
     /// <summary>
         /// <#=row["Description"]#>
         /// </summary>
         public <#= manager.TransFromSqlType(row["DataType"].ToString(),row["IsNullable"].ToString())#>  <#=row["ColumnName"]#>{ get; set; }
     <#}
     #>
     #endregion
     }
 }

 <#+
     public class ModelManager
     {
         /// <summary>
         /// 数据库连接字符串
         /// </summary>
         private const string CONNECTION_STRING="Data Source=.;Initial Catalog=dbserver;User ID=sa;pwd=000000";
         /// <summary>
         /// 用户信息表名
         /// </summary>
         private const string PERSONINFO_TABLE_NAME = "tbOptAuthor";
         /// <summary>
         /// 根据表名查询表结构信息
         /// SQL Server 2005写法
         /// </summary>
         private const string SELECT_SCHEMA_BY_TABLE_NAMEs = @"SELECT
                                                             d.name AS TableName,
                                                             a.colorder AS ColumnID,
                                                             a.name AS ColumnName,
                                                             b.name AS DataType,
                                                             g.[value] AS Description,
                                                             CASE WHEN a.isnullable = 0 THEN 'false'
                                                                 ELSE 'true'
                                                             END AS IsNullable
                                                             FROM syscolumns a left join systypes b
                                                             on a.xtype=b.xusertype
                                                             inner join sysobjects d
                                                             on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'
                                                             left join sys.extended_properties g
                                                             on a.id=g.major_id AND a.colid = g.minor_id
                                                             WHERE d.[name] ='{0}'
                                                             order by a.id,a.colorder";

         /// <summary>
         /// 根据表名查询表结构信息
         /// SQL Server 2000写法
         /// </summary>
         private const string SELECT_SCHEMA_BY_TABLE_NAME = @"SELECT (
                                                             case when a.colorder=1 then d.name else '' end) N'表名',
                                                             a.colorder N'字段序号',a.name N'ColumnName',
                                                             (case when COLUMNPROPERTY( a.id,a.name,'IsIdentity')=1 then '√'else '' end) N'标识',
                                                             (case when (SELECT count(*) FROM sysobjects
                                                             WHERE (name in (SELECT name FROM sysindexes
                                                             WHERE (id = a.id) AND (indid in
                                                             (SELECT indid FROM sysindexkeys
                                                             WHERE (id = a.id) AND (colid in
                                                             (SELECT colid FROM syscolumns
                                                             WHERE (id = a.id) AND (name = a.name))))))) AND
                                                             (xtype = 'PK'))>0 then '√' else '' end) N'主键',b.name N'DataType',a.length N'占用字节数',
                                                             COLUMNPROPERTY(a.id,a.name,'PRECISION') as N'长度',isnull(COLUMNPROPERTY(a.id,a.name,'Scale'),0) as N'小数位数',
                                                             (case when a.isnullable=1 then '√'else '' end) N'IsNullable',
                                                             isnull(e.text,'') N'默认值',isnull(g.[value],'') AS N'Description'
                                                             --into ##tx
                                                             FROM syscolumns a left join systypes b on a.xtype=b.xusertype
                                                             inner join sysobjects d on a.id=d.id and d.xtype='U' and d.name<>'dtproperties'
                                                             left join syscomments e on a.cdefault=e.id
                                                             left join sysproperties g on a.id=g.id AND a.colid = g.smallid
                                                             where d.name='{0}'
                                                             order by object_name(a.id),a.colorder";

         /// <summary>
         /// 获得数据连接
         /// </summary>
         /// <returns></returns>
         private SqlConnection GetConnection()
         {
             return new SqlConnection(CONNECTION_STRING);
         }
         /// <summary>
         /// 释放连接
         /// </summary>
         /// <param name="con"></param>
         private void ReleaseConnection(SqlConnection con)
         {
             if (con != null)
             {
                 if (con.State == ConnectionState.Open)
                 {
                     con.Close();
                 }
             }
         }

         /// <summary>
         ///
         /// </summary>
         /// <param name="tableName"></param>
         public DataTable GetTableSchema(string tableName)
         {
             DataTable dt;
             using (SqlConnection con = GetConnection())
             {
                 con.Open();

                 SqlCommand cmd = con.CreateCommand();
                 cmd.CommandText = string.Format(SELECT_SCHEMA_BY_TABLE_NAME,tableName);
                 cmd.CommandType = CommandType.Text;

                 SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                 DataSet ds = new DataSet();
                 adapter.Fill(ds);
                 dt = ds.Tables[];
             }

             return dt;
         }
         /// <summary>
         ///
         /// </summary>
         public void Generate()
         {
             DataTable table = GetTableSchema(PERSONINFO_TABLE_NAME);

             if (table != null && table.Rows.Count > )
             {
                 foreach (DataRow row in table.Rows)
                 {
                     Console.WriteLine("public class {0}", row["TableName"]);
                     Console.WriteLine("public {0} {1}", TransFromSqlType(row["DataType"].ToString(),row["IsNullable"].ToString()), row["ColumnName"]);
                 }
             }
         }
         /// <summary>
         /// SQL
         /// </summary>
         /// <param name="type"></param>
         /// <returns></returns>
         public string TransFromSqlType(string type,string isNull)
         {
             string typeStr="";
             switch (type)        //数据库的数据类型转换为对应的C#的数据类型，不是很完整
             {
                 case "datetime":
                 case "smalldatetime":
                     typeStr=isNull=="true"? "?":"";
                     return "DateTime"+typeStr;
                     break;
                 case "int":
                 case "smallint":
                     typeStr=isNull=="true"? "?":"";
                     return "int"+typeStr;
                     break;
                 case "bit":
                     typeStr=isNull=="true"? "?":"";
                     return "bool"+typeStr;
                     break;
                 case "float":
                     typeStr=isNull=="true"? "?":"";
                     return "double"+typeStr;
                     break;
                 case "decimal":
                 case "money":
                 case "smallmoney":
                 case "numeric":
                     typeStr=isNull=="true"? "?":"";
                     return "decimal"+typeStr;
                     break;
                 case "uniqueidentifier":
                     typeStr=isNull=="true"? "?":"";
                     return "Guid"+typeStr;
                     break;
                 default:
                     return "string"+typeStr;
                     break;
             }
         }
     }
 #>

生成后的实体：

 /* ****************************************************************************************
  * 版权所有：西安xxx软件有限公司
  * 用    途：数据传输对象(DTO)
  * 结构组成：
  * 作    者：xxx
  * 创建日期：2012-12-28 11:32:47
  * 历史记录：
  * ****************************************************************************************
  * 修改人员：wgx
  * 修改日期：2014-12-28 11:32:47
  * 修改说明：新增一个针对sql 2000数据库的查询方法
  * ****************************************************************************************/
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;

 namespace wgx.Model
 {
     [Serializable]
     /// <summary>
     /// DTO_OptAuthor
     /// </summary>
     public class DTO_OptAuthor
     {
         #region 属性
         /// <summary>
         /// 用户组代码
         /// </summary>
         public string  strGroupCode{ get; set; }
         /// <summary>
         /// 功能模块代码
         /// </summary>
         public string  strCaseCode{ get; set; }
         /// <summary>
         /// 权限级别
         /// </summary>
         public string  strLevel{ get; set; }
         /// <summary>
         /// 组数据级别
         /// </summary>
         public string  strGroupLevel{ get; set; }
         #endregion
     }
 }

使用过程可能遇到的问题：

解决办法：