在winform中查询的连接打开和关闭需要什么？

Question

在我的形式中,有很多组合框.我想将不同的表数据加载到组合框.我试图这样做,但由于连接打开和关闭编码,代码非常慢.

当我在没有关闭连接的情况下运行两个命令并打开它时抛出一个异常.

已经有一个与此Connection关联的开放DataReader,必须先关闭它.

如何在程序中删除此打开和关闭？这是我的代码:

string MyConString = ConfigurationManager.ConnectionStrings["College_Management_System.Properties.Settings.cmsConnectionString"].ConnectionString;
MySqlConnection connection = new MySqlConnection(MyConString);
MySqlCommand command = connection.CreateCommand();
MySqlDataReader Reader;
command.CommandText = "select name from course_master";
connection.Open();
Reader = command.ExecuteReader();
while (Reader.Read())
{
    cmbo_course.Items.Add(Reader[0].ToString());
}

command.CommandText = "select name from country_master";
Reader = command.ExecuteReader();
while (Reader.Read())
{
    cmbo_perCountry.Items.Add(Reader[0].ToString());
    cmbo_country.Items.Add(Reader[0].ToString());
}
connection.Close();

Answer 1

尝试使用这个

Reader = command.ExecuteReader( CommandBehavior.CloseConnection() );