comboBox 디비 데이터로 채워넣기

ComboBox에 데이터 채워넣기.

using System.Data.SqlClient;

SqlConnection objcon = new SqlConnection("Data Source=;Initial Catalog=Project;uid=sa;pwd=;");
objcon.Open();
SqlCommand com = new SqlCommand(); 
SqlDataAdapter da=new SqlDataAdapter();
DataSet ds=new DataSet();
da.TableMappings.Add("Table","category");
com.Connection=objcon;
com.CommandType=CommandType.Text;
com.CommandText="SELECT cat_name FROM category";
da.SelectCommand=com;
da.SelectCommand.ExecuteNonQuery();
da.Fill(ds);
cmb_cat.DataSource=ds.DefaultViewManager;
cmb_cat.DisplayMember="category.cat_name";