How should I cast a DataTable for assignment to DataGrid.ItemsSource?

Question

I am trying to learn WPF, and trying to populate a WPF DataGrid with data from a MySQL database. The relevant code is:

        dataGrid.DataContext = myMySQL.DBD         


        

Answer 1

private DataTable GetNewStaffCode()
       {
           Mod_Staff stafmodules = new Mod_Staff();
           staffcode = txtStaffCode.Text.ToString();
           DataTable dtstaffcode=stafmodules.GetNewStaffCode(staffcode);
           for (int j = 0; j < dtstaffcode.Rows.Count; j++)
           {
               staffcode ="ST"+ Convert.ToString(j);
           }

The Error Message are:

Cannot implicitly convert type 'System.Data.DataTable' to 'string'

And

Real_Estate_Management_System.StaffEntry.GetNewStaffCode()': not all code paths return a value D:\Shwe Ain Real Estate Management\Real Estate Management By May Mee Tun\Real_Estate_App\Real_Estate_Management_System\Real_Estate_Management_System\UI\StaffEntry.cs 329 30 Real_Estate_Management_System

           txtStaffCode.Refresh();
       }

public DataTable GetNewStaffCode(string staffcode)
    {
        String query = "Select staff_code from tblStaffType";
        if (CN.State == ConnectionState.Closed) CN.Open();
        SqlCommand cmd = new SqlCommand(query, CN);
        DataTable dt = new DataTable();
        SqlDataAdapter adp = new SqlDataAdapter(cmd);
        adp.Fill(dt);
        return dt;
    }