Processing SQL query result in PHP, then inserting again within same function

Question

I'm trying to make a function work, where I ask for a number of free seats left in a car, and if executed, it subtracts 1 from the result and updates the cell in database.

Sql statements must be correct... am I missing out on anything else?

function seatCalc($id){

    $stmt=$this->connection->prepare("SELECT seats_left FROM drive WHERE id=?");
    $stmt->bind_param("i", $id);
    $stmt->bind_result($seat_count);
    $stmt->execute();

    return $seat_count;

    if($seat_count >= 1){

        $seat_count -= 1;

        $stmt=$this->connection->prepare("UPDATE drive SET seats_left=? WHERE id=?");
        $stmt->bind_param("ii", $seat_count, $id);
        $stmt->execute();
    }

}

It's a part of my university project and unfortunately, I can't reach my professor at the moment.

Thank you in advance!

Uuh, a horrible typo here, ($seat_count >= 1) or ($seat_count > 0) both do not give any result, corrected wrong comparison here — andri007
– andri007, Commented Dec 15, 2014 at 20:29

mopo922 · Accepted Answer · 2014-12-15 20:29:44Z

4

Your return statement breaks you out of the function before the if block gets processed.

answered Dec 15, 2014 at 20:29

mopo922

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Comments

vp_arth · Accepted Answer · 2014-12-15 20:34:33Z

0

your condition is incorrect;
you have unreached statements after return;

Here is code:

function seatCalc($id){
  $stmt=$this->connection->prepare("SELECT seats_left FROM drive WHERE id=?");
  $stmt->bind_param("i", $id);
  $stmt->bind_result($seat_count);
  $stmt->execute();
  if($seat_count > 0){
    $stmt=$this->connection->prepare("UPDATE drive SET seats_left=seats_left-1 WHERE id=?");
    $stmt->bind_param("i", $id);
    $stmt->execute();
  }
  return $seat_count;
}

Also you can substract one with database..

edited Dec 15, 2014 at 20:34

answered Dec 15, 2014 at 20:29

vp_arth

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2 Comments

u_mulder Over a year ago

$seat_count > 0 is the same as $seat_count >= 1

andri007 Over a year ago

Yess, I dont know why I couldn't think of subtracting one with database directly.. Thank you sir!

ksealey · Accepted Answer · 2014-12-15 20:38:32Z

0

Oh boy

function seatCalc($id){

    $stmt=$this->connection->prepare("SELECT seats_left FROM drive WHERE id=:i");
    $stmt->bind_param(":i", $id);
    $stmt->execute();

    $row = $stmt->fetch(PDO::FETCH_ASSOC);
    $seat_count = intval($row['seats_left']);

    if($seat_count > 0){

        $seat_count -= 1;

        $stmt=$this->connection->prepare("UPDATE drive SET seats_left=seats_left-1 WHERE id=:id");
        $stmt->bind_param(":id", $id);
        $stmt->execute();
    }
    return $seat_count;
}

answered Dec 15, 2014 at 20:38

ksealey

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