ASP.NET数据库连接类（SqlDBHelper）

第一步：创建一个名为SqlDBHelper的类，用来作为联通数据库和系统之间的桥梁。

第二步：引入命名空间,如果System.Configuration、System.Transcations这两个命名空间找不到，可在项目目录下的【引用】=》添加引用【框架】中找到，添加引用即可。

 using System.Data;
 using System.Data.SqlClient;
 using System.Configuration;
 using System.Transactions;

第三步：在配置文件中添加数据库连接地址。

 <configuration>
     <startup>
         <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
     </startup>
   <connectionStrings>
     <add name="MES" connectionString="Data Source=数据库IP;Database=数据库名;User ID=用户名;Password=连接密码;" providerName="System.Data.SqlClient;"/>
   </connectionStrings>
 </configuration>

第四部：在SqlDBHelper中编写读取配置文件中连接数据库字段：

  private static readonly string connectionString = ConfigurationManager.ConnectionStrings["MES"].ToString();

如果ConfigurationManager提示错误，同第二步操作即可。

第五步：编写操作Sql命令的方法（增删改查）：

  public static string DataBase
         {
             get {
                 SqlConnection conn = new SqlConnection();
                 string db = conn.Database;  //获取当前数据库或使用的数据库名称
                 conn.Dispose();
                 return db;
             }
         }

         #region 为SQL命令做提前的参数设定
         /// <summary>
         /// 为cmd做执行前的参数设定
         /// </summary>
         /// <param name="cmd">cmd命令对象</param>
         /// <param name="conn">连接对象</param>
         /// <param name="trans">事务对象</param>
         /// <param name="cmdType">命令类型</param>
         /// <param name="cmdText">SQL命令文本</param>
         /// <param name="cmdParms">在命令文本中要使用的SQL参数</param>
         private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
         {
             if (conn.State != System.Data.ConnectionState.Open)  //如果连接通道未打开，则打开连接通道
                 conn.Open();
             cmd.CommandTimeout = ;  //等待时间
             cmd.Connection = conn;  //为命令对象设置连接通道
             cmd.CommandText = cmdText; //为命令对象设置SQL文本
             if (trans != null)   //如果存在事务，则为命令对象设置事务
                 cmd.Transaction = trans;
             cmd.CommandType = cmdType;  //设置命令类型（SQL文本/存储过程）
             if (cmdParms != null)  //如果参数集合不为空，为命令对象添加参数
                 cmd.Parameters.AddRange(cmdParms); 

         }
         #endregion

         #region sql 增删改
         /// <summary>
         /// 执行SQL命令 增删改（无参数）
         /// </summary>
         /// <param name="cmdText">SQL命令语句</param>
         /// <returns></returns>
         public static int ExecuteCommand(string cmdText)  //重载
         {
             return ExecuteCommand(cmdText,null);
         }

         /// <summary>
         /// 执行SQL命令 增删改（带参数）
         /// </summary>
         /// <param name="cmdText">SQL命令语句</param>
         /// <param name="parameters">参数</param>
         /// <returns></returns>
         public static int ExecuteCommand(string cmdText, SqlParameter[] parameters)
         {
             return ExecuteCommand(cmdText,CommandType.Text,parameters);
         }

         /// <summary>
         /// 执行SQL命令 增删改（带参数）
         /// </summary>
         /// <param name="cmdText">SQL命令</param>
         /// <param name="cmdType">命令类型</param>
         /// <param name="commandParameters">参数集合</param>
         /// <returns></returns>
         public static int ExecuteCommand(string cmdText, CommandType cmdType, params SqlParameter[] commandParameters)
         {
             using (TransactionScope transcation = new TransactionScope())  //TransactionScope 使代码块成为事务性代码
             {
                 int res = ;
                 try
                 {
                     SqlCommand cmd = new SqlCommand();
                     using (SqlConnection conn = new SqlConnection(connectionString))
                     {
                         PrepareCommand(cmd,conn,null,cmdType,cmdText,commandParameters);

                         res = cmd.ExecuteNonQuery();  //执行SQL并返回受影响的行数
                         transcation.Complete();  //指示范围内的操作都已经完成
                     }
                 }
                 catch (Exception ex)
                 {
                     throw ex;
                 }
                 return res;
             }
         }

         /// <summary>
         /// 执行SQL命令  增删改
         /// </summary>
         /// <param name="cmdText">SQL命令</param>
         /// <param name="trans">事务对象</param>
         /// <param name="cmdType">命令类型</param>
         /// <param name="parameters">命令参数</param>
         /// <returns></returns>
         public static int ExecuteCommand(string cmdText, SqlTransaction trans, CommandType cmdType, SqlParameter[] parameters)
         {
             SqlCommand cmd = new SqlCommand();
             PrepareCommand(cmd,trans.Connection,trans,cmdType,cmdText,parameters);
             int res = ;
             try
             {
                 res = cmd.ExecuteNonQuery();
             }
             catch (Exception ex)
             {
                 throw ex;
             }
             cmd.Parameters.Clear();
             return res;
         }
         #endregion

         #region sql 查询操作
         /// <summary>
         /// 执行SQL命令  查询
         /// </summary>
         /// <param name="sqlStr">SQL命令语句</param>
         /// <returns></returns>
         public static DataTable GetDataTable(string sqlStr)
         {
             return GetDataTable(sqlStr,null);
         }

         /// <summary>
         /// 执行SQL命令  查询
         /// </summary>
         /// <param name="sqlStr">SQL命令</param>
         /// <param name="parameters">参数集合</param>
         /// <returns></returns>
         public static DataTable GetDataTable(string sqlStr, SqlParameter[] parameters)
         {
             return GetDataTable(sqlStr,CommandType.Text,parameters);
         }

         /// <summary>
         /// 执行SQL命令
         /// </summary>
         /// <param name="sqlStr">SQL命令</param>
         /// <param name="cmdType">命令类型</param>
         /// <param name="parameters">参数集合</param>
         /// <returns></returns>
         public static DataTable GetDataTable(string sqlStr, CommandType cmdType, SqlParameter[] parameters)
         {
             using (SqlConnection connection = new SqlConnection(connectionString))
             {
                 SqlCommand cmd = new SqlCommand(sqlStr,connection);
                 cmd.CommandTimeout = ;
                 cmd.CommandType = cmdType;
                 if (parameters != null)
                     cmd.Parameters.AddRange(parameters);
                 SqlDataAdapter da = new SqlDataAdapter(cmd);
                 DataTable dt = new DataTable();
                 try
                 {
                     da.Fill(dt);
                 }
                 catch (Exception ex)
                 {
                     throw ex;
                 }
                 cmd.Parameters.Clear();
                 return dt;
             }
         }

         public static DataTable GetDataTable(string sqlStr,string con,int i)
         {
             SqlConnection conn = new SqlConnection(con);
             conn.Open();
             SqlCommand cmd = new SqlCommand(sqlStr,conn);
             SqlDataAdapter da = new SqlDataAdapter(cmd);
             DataTable dt = new DataTable();
             da.Fill(dt);
             conn.Close();
             cmd.Dispose();
             da.Dispose();
             return dt;
         }

         /// <summary>
         /// 执行SQL 查询
         /// </summary>
         /// <param name="cmdText">SQL命令语句</param>
         /// <returns></returns>
         public static object GetScalar(string cmdText)
         {
             return GetScalar(cmdText,null);
         }

         /// <summary>
         /// 执行SQL  查询
         /// </summary>
         /// <param name="cmdText">SQL命令</param>
         /// <param name="parameters">参数集合</param>
         /// <returns>第一行第一列（object类型）</returns>
         public static object GetScalar(string cmdText, SqlParameter[] parameters)
         {
             return GetScalar(cmdText,CommandType.Text,parameters);
         }

         /// <summary>
         /// 执行SQL 查询
         /// </summary>
         /// <param name="cmdText">SQL命令</param>
         /// <param name="cmdType">命令类型</param>
         /// <param name="parameters">参数集合</param>
         /// <returns>第一行第一列的值（object类型）</returns>
         public static object GetScalar(string cmdText, CommandType cmdType, SqlParameter[] parameters)
         {
             object res = ;
             SqlCommand cmd = new SqlCommand();
             using (SqlConnection conn = new SqlConnection(connectionString))
             {
                 PrepareCommand(cmd,conn,null,cmdType,cmdText,parameters);
                 try
                 {
                     res = cmd.ExecuteScalar();
                 }
                 catch(Exception ex)
                 {
                     throw ex;
                 }
                 cmd.Parameters.Clear();
                 return res;
             }
         }

         public static void Insert_NewData(DataTable dt, string tableName)
         {
             SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(connectionString,SqlBulkCopyOptions.UseInternalTransaction);
             sqlBulkCopy.DestinationTableName = tableName;//数据库中的表名

             sqlBulkCopy.WriteToServer(dt);
             sqlBulkCopy.Close();
         }
         #endregion

至此，SqlDBHelper类完成，在需要时直接调用即可。