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; 
        } 
    } 
}