使用mysqli :: store_result（）后获取数据

Question

I am selecting data from my database in the following way: As expected I get one row as result and want to extract the lat and lon data from it:

    $prep_stmt = "SELECT lat, lon FROM members WHERE id = ? LIMIT 1";   
    $stmt = $mysqli->prepare($prep_stmt);

      if ($stmt) {
        $stmt->bind_param('i', $user_id);
        $stmt->execute();
        $result = $stmt->store_result();

        if ($stmt->num_rows == 1) {
          logC("user exists");
          logC("extract lat, lon!");
        } 
      }

I tried using $stmt->fetch() and extracting it from the $result variable but without success. What is the proper way to do it?

Answer 1

Since you're expecting just one result:

  if ($stmt = $mysqli->prepare($prep_stmt)) {
    $stmt->bind_param('i', $user_id);
    $stmt->execute();
    $stmt->bind_result($lat, $lon);

    if(($result = $stmt->fetch()) == true){
      echo "'$lat' and '$lon'";
    } elseif($result == false) {
      echo 'db error';
    } else {
      echo 'no results'; // $result == null
    }


  }

If you have multiple rows, $stmt->fetch() will bind the next result to the same variables so you can do:

while($stmt->fetch()){
  echo $lat, $lon;
}

It is just 1 way of many.. just read the documentation.