NET连接MySQL数据库的CRUD

//获得Web.config中的配置信息
        string sqlCconnStr = ConfigurationManager.ConnectionStrings["MySqlStr"].ConnectionString;
        MySqlConnection sqlCon = new MySqlConnection(sqlCconnStr);//连接数据库 


        //打开连接
        sqlCon.Open();

        //SQL语句
        string sql = "insert into user (username,password) values ('csdn','csdn')";


        //获得MySsqlCommand
        MySqlCommand cmd = new MySqlCommand(sql, sqlCon);

        //执行SQL
         cmd.ExecuteNonQuery();


        cmd = null;
        sqlCon.Close();
        sqlCon = null;

//获得Web.config中的配置信息
        string sqlCconnStr = ConfigurationManager.ConnectionStrings["MySqlStr"].ConnectionString;
        MySqlConnection sqlCon = new MySqlConnection(sqlCconnStr);//连接数据库 


        //打开连接
        sqlCon.Open();

        //SQL语句
        string sql = "delete from user where id = 3";


        //获得MySsqlCommand
        MySqlCommand cmd = new MySqlCommand(sql, sqlCon);

        //执行SQL
         int updateCount=cmd.ExecuteNonQuery();
        if (updateCount > 0)
        {
            Response.Write("删除成功");
        }
        else {
            Response.Write("删除失败");
        }


        cmd = null;
        sqlCon.Close();
        sqlCon = null;

  //获得Web.config中的配置信息
        string sqlCconnStr = ConfigurationManager.ConnectionStrings["MySqlStr"].ConnectionString;
        MySqlConnection sqlCon = new MySqlConnection(sqlCconnStr);//连接数据库 


        //打开连接
        sqlCon.Open();

        //SQL语句
        string sql = "update user set username = 'ndsc' where password = 'csdn'";


        //获得MySsqlCommand
        MySqlCommand cmd = new MySqlCommand(sql, sqlCon);

        //执行SQL
         int updateCount=cmd.ExecuteNonQuery();
        if (updateCount > 0)
        {
            Response.Write("更新成功");
        }
        else {
            Response.Write("更新失败");
        }


        cmd = null;
        sqlCon.Close();
        sqlCon = null;

             //获得Web.config中的配置信息
        string sqlCconnStr = ConfigurationManager.ConnectionStrings["MySqlStr"].ConnectionString;
        MySqlConnection sqlCon = new MySqlConnection(sqlCconnStr);//连接数据库 

        //打开连接
        sqlCon.Open();

        //SQL语句
        string sql = "select username from user ";

        //获得MySsqlCommand
        MySqlCommand cmd = new MySqlCommand(sql, sqlCon);

        //执行SQL并且返回查询结果
        MySqlDataReader dataReader = cmd.ExecuteReader();

        //处理返回结果
        while (dataReader.Read())
        {

            //string obj = dataReader.GetString(0);
            string obj = dataReader.GetString("username");
            //Console.WriteLine(obj);
            Label1.Text += obj;
        }

        cmd = null;
        sqlCon.Close();
        sqlCon = null;