order select

the first order (by pos)

It returns the earliest open order in the terminal. Not necessarily the oldest order on the current chart nor the oldest opened by the EA. Always use a select loop. Always count down when there could be multiple open orders (multiple charts) when modifying/closing/deleting. If you actually need the first order or last, just remember the ticket and reselect.

int ticketLast=0, ticketFirst=0;
for(pos = OrdersTotal()-1; pos >= 0 ; pos--) if (
    OrderSelect(pos, SELECT_BY_POS)                 // Only my orders w/
&&  OrderMagicNumber()  == magic.number             // my magic number
&&  OrderSymbol()       == Symbol() ){              // and my pair.
    if (ticketLast == 0)    ticketLast = OrderTicket();
    ticketFirst = OrderTicket();
}
if (ticketFirst != 0 && OrderSelect(ticketFirst, SELECT_BY_TICKET){
    // do something with the first.
}