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 = 60;  //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 = 0;
                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 = 0;
            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 = 60;
                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 = 0;
            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。