I am trying to update a user portfolio table to update when a user sells a share of a item. I want to subtract one from shares until the desired number of shares to sell hits 0. Then when the shares of that item reaches 0 I want to delete that row from the users portfolio. I believe I have to use a while loop and the TOP command because users often have made many different purchases of the same item so they are stored in different records in the table. I think am I pretty close but I can not get either the update or delete query in my loop to run.
while ($sharesToSell >0)
{
$sql="UPDATE TOP (1) portfolio SET shares= shares-1 WHERE
userid='".$userid."'AND songid='".$songID."';";
$result6 = $connection->query($sql);
$sharesToSell-=1;
if($sharesToSell>0)
{
$sql="DELETE FROM PORTFOLIO WHERE shares='0';";
$result7 = $connection->query($sql);
}
}