Undefined variable of a sum in PHP [closed]

Answer 1

move your

$total=0; 

above your while and the undefined error should be gone. The reasons is clear, you're trying to add $price to undefined variable.

Answer 2

Move total above the while. and then use += for less verbose code.

$total=0;
while ($data=mysql_fetch_array($result)){
  $total+=$price;
}