Minus 1

[june_c21]

hi , i want  to select qty from master where id=$id , then i want to minus the qty = qty -1  and update in the query .

here is my code . can tell me what went wrong ?

 

$query= "SELECT qty FROM master where id=$id";
$result = mysql_query($query,$dblink);
  while($myrow = mysql_fetch_row($result))
  {
qty -= 1;

  $query = "UPDATE master SET qty='$qty' WHERE id= $id";
$result = mysql_query($query,$dblink);

  }

 

thanks

 

[MMDE]

$qnt=-1;
mysql_query('UPDATE master SET qty=qty+'.$qnt.' WHERE id='.$id) or die(mysql_error());

or if you only want to minus 1

mysql_query('UPDATE master SET qty=qty-1 WHERE id='.$id) or die(mysql_error());

[PFMaBiSmAd]

You only need these two lines of code -

 

$query = "UPDATE master SET qty=qty - 1 WHERE id= $id";
$result = mysql_query($query,$dblink);

[june_c21]

thanks