dropdown list in datagrid

hi all,

I placed drop down list control in datagrid first column.and I wants to add values to drop down list.Datagrid should show only one row.

I added values to drop down list control by firing item bound event of datagrid and I binded the grid with datasource the one I added to drop down list.In my database 4 rows are there.So datagrid is showing 4 rows.