مهم جدا وضرورى _مشروع تخرج

	Private Sub FillallCombo(ByVal mComboBox As Object, ByVal mSql As String)

		Dim rs As SqlClient.SqlDataReader
		Dim mCom As New SqlClient.SqlCommand(mSql, Conn)

		rs = mCom.ExecuteReader

		While rs.Read()

			mComboBox.Items.Add(rs.Item(1))

		End While

		rs.Close()
		mCom.Dispose()

	End Sub

And Call this Sub using

Call FillallCombo(ComboBox1, "select serial ,desc1 from countries ")

And To Clear DatagirdView

DataGridview.Clear

Or

DataGridViews.RowCount=1