SqlHelper其实是我们自己编写的一个类，使用这个类目的就是让使用者更方便、更安全的对数据库的操作，既
是除了在SqlHelper类以外的所有类将不用引用对数据库操作的任何类与语句，无须担心数据库的连接与关闭的问题。

{       public class SQLHelper       {           private string strConn = null;           private SqlConnection Conn = null;           private SqlCommand Cmd = null;           private SqlDataReader Sqlsdr = null;           public SQLHelper()           {               //利用反射连接数据库               strConn = ConfigurationManager.ConnectionStrings["strConn"].ConnectionString;               //strConn = "data source=192.168.24.83;initial catalog=NewsSystem;user id=sa;password=123456";               Conn = new SqlConnection(strConn);           }                /// <summary>           /// 状态           /// </summary>           /// <returns>SqlConnection</returns>           private SqlConnection GetConn()           {               if (Conn.State == ConnectionState.Closed)               {                   Conn.Open();               }               return Conn;           }                /// <summary>           /// 执行不带参数的增删改操作           /// </summary>           /// <param name="CmdText">执行的SQL语句或存储过程</param>           /// <param name="CmdType">类型</param>           /// <returns>增删改的操作数</returns>                public int ExecuteNonQuery(string CmdText, CommandType CmdType)           {               //数据库连接语句               int res;               try               {                   Cmd = new SqlCommand(CmdText, GetConn());                   Cmd.CommandType = CmdType;                   res = Cmd.ExecuteNonQuery();                    }               catch (Exception ex)               {                        throw ex;               }               finally               {                   if (Conn.State == ConnectionState.Open)                   {                       Conn.Close();                   }               }               return res;           }                /// <summary>           /// 执行带参数的增删改操作           /// </summary>           /// <param name="CmdText">执行的SQL语句或存储过程</param>           /// <param name="Parameters">参数</param>           /// <param name="CmdType">类型（SQL语句或存储过程）</param>           /// <returns>增删改的操作数</returns>           public int ExecuteNonQuery(string CmdText, SqlParameter[] Parameters, CommandType CmdType)           {               int res;               try               {                   Cmd.Parameters.AddRange(Parameters);                   Cmd = new SqlCommand(CmdText, GetConn());                   Cmd.CommandType = CmdType;                   res = Cmd.ExecuteNonQuery();               }               catch (Exception ex)               {                        throw ex;               }               finally               {                   if (Conn.State == ConnectionState.Open)                   {                       Conn.Close();                   }               }               return res;           }                     /// <summary>           /// 不带参数的查询           /// </summary>           /// <param name="CmdText">执行的SQL语句或存储过程</param>           /// <param name="CmdType">类型</param>           /// <returns>查询的数据</returns>           public DataTable ExecuteQuery(string CmdText, CommandType CmdType)           {               DataTable dt = new DataTable();                    using (Sqlsdr = Cmd.ExecuteReader(CommandBehavior.CloseConnection))               {                   Cmd = new SqlCommand(CmdText, GetConn());                   Cmd.CommandType = CmdType;                   dt.Load(Sqlsdr);               }               return dt;           }                /// <summary>           /// 带参数的查询           /// </summary>           /// <param name="CmdText">SQL语句或存储过程</param>           /// <param name="Parameters">参数</param>           /// <param name="CmdType">类型</param>           /// <returns>查询的数据</returns>           public DataTable ExecuteQuery(string CmdText, SqlParameter[] Parameters, CommandType CmdType)           {               DataTable dt = new DataTable();                    using (Sqlsdr = Cmd.ExecuteReader(CommandBehavior.CloseConnection))               {                   Cmd = new SqlCommand(CmdText, GetConn());                   Cmd.CommandType = CmdType;                   Cmd.Parameters.AddRange(Parameters);                   dt.Load(Sqlsdr);               }               return dt;           }       }   }