How to populate gridview with a custom sql query instead of selecting datasource and table

public partial class Form1 : Form
{
    private string connectionString = "Server=(local);Database=Retail_POS_System;Trusted_Connection=True;";
    SqlConnection sqlConnection;
    SqlCommand sqlCommand;
    SqlDataReader sqlDataReader;
    SqlDataAdapter sqlDataAdapter;
    DataSet ds;
    public Form1()
    {
        InitializeComponent();
        this.radGridView1.AutoSizeColumnsMode = Telerik.WinControls.UI.GridViewAutoSizeColumnsMode.Fill;
        sqlConnection = new SqlConnection(connectionString);
        sqlConnection.Close();
        sqlConnection.Open();
        sqlCommand = new SqlCommand("Select POSDeviceDefination.NAME, POSDeviceType.DeviceName From POSDeviceDefination INNER JOIN POSDeviceType On POSDeviceDefination.TYPE = POSDeviceType.DeviceID", sqlConnection);           
        sqlDataReader = sqlCommand.ExecuteReader(CommandBehavior.CloseConnection);

        if (sqlDataReader.HasRows)
        {
            ds = new DataSet();
            sqlDataReader.Close();
            sqlDataAdapter = new SqlDataAdapter(sqlCommand);
            sqlDataAdapter.Fill(ds);
            DataTable table = ds.Tables[0];
            this.radGridView1.DataSource = table;
        }

        sqlConnection.Close();
    }
}