Private Sub combobox_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles combobox.SelectedIndexChanged
Dim sql As String
sql = "select ... from ... where ... ='" & combobox.Text & "'"
Dim da As New OleDbDataAdapter(sql, Conn)
Dim ds As New DataSet
Dim dtr As DataRow
da_floor.Fill(ds, "tmp")
For Each dtr In ds.Tables("tmp").Rows
textbox.text = dtr("ชื่อ column")
Next
End Sub