Reader always returns NULL - sql-server

Question

I'm new to C#. I want to write an application that can easily connect to a SQL Server database. I have a separate DBConnection class, and I want to call this class from any form.
The problem is that my "reader" always returns Null.
class DBconnection
{
private SqlConnection conn;
private SqlCommand cmd;
private SqlDataReader rdr;
private DataTable dt;
private SqlConnection MyConnection
{
get
{
if (this.conn == null)
{
this.conn = new SqlConnection(DrivingSchool.Properties.Settings.Default.cdsConnectionString);
}
return conn;
}
}
private SqlCommand MyCommand
{
get
{
if (cmd == null)
{
cmd = new SqlCommand();
MyCommand.Connection = conn;
}
return cmd;
}
}
public DataTable RunQuery(string query)
{
dt = new DataTable();
MyCommand.CommandText = query;
MyCommand.Connection = conn;
MyConnection.Open();
rdr = MyCommand.ExecuteReader(CommandBehavior.CloseConnection);
if(rdr.HasRows)
{
dt.Load(rdr);
}
MyConnection.Close();
return dt;
}
}

Answer 1

It seems to me that in factoring out the creation of the connection and SqlCommand that you have over-complicated your code.
To fill a DataTable, you should use an SqlDataAdapter (or the appropriate DataAdapter for whatever database you use), something like this:
static public DataTable GetDataTableFromQuery(string queryString)
{
DataTable dt = null;
string connStr = DrivingSchool.Properties.Settings.Default.cdsConnectionString;
using (SqlDataAdapter da = new SqlDataAdapter(queryString, connStr))
{
da.Fill(dt);
}
return dt;
}