how to check stock c#

Question

I want to check item in the stock table, if in the stock of items is not enough then there will be notification "Item Not enough"

if (cm_status.SelectedItem.TosString() == "OUT")
{
   //check Stock QTY in Tabel Stock  <----
   i want ceck Stock in here after Update
}
Else
{
  cmd = New SqlCommand ("UPDATE Tb_Stock Set Qty= Qty - '"+ txt_Qty.text +"' WHERE Code_Items= '"+ txt_codeItem.text +"'",conn);
}