从数据库中检索多个记录

Question

In my database 'coordinates' there are four columns id bus_id latitude longitude where a user having a particular bus_is send its long, lat on a regular interval of time. I want to retrieve most updated value for each user. Here is my code:

<?php
      define('HOST','localhost');
      define('USER','root');
      define('PASS','1234');
      define('DB','coordinates');
      $con = mysqli_connect(HOST,USER,PASS,DB);


     $arr=[];
      for($x=1; $x=3; $x++){
      $query = "SELECT id, longitude, latitude FROM data WHERE bus_id= ".$x." ORDER BY id DESC limit 1 offset 1 " ;
      $qry_result = mysqli_query($con,$query);// or die(mysqli_error());
      }   
       // Insert a new row in the table for each person returned
       while($row = mysqli_fetch_array($qry_result)) {

         array_push($arr, [
           'lat'=>['$latitude'],
           'lng'=>['$longitude'],
           //'recs'=>$recs
         ]);
       }

$record= json_encode($arr);
echo $arr;    
?>

when i run this code it doesn't give me right output. Please tell me where am i wrong.

Answer 1

You should run the while into the for loop. Try this code :

    <?php
      define('HOST','localhost');
      define('USER','root');
      define('PASS','123456');
      define('DB','test');
      $con = mysqli_connect(HOST,USER,PASS,DB);

     $arr=[];
      for($x=1; $x<=3; $x++){
       $query = "SELECT id, longitude, latitude FROM data WHERE bus_id= ".$x." ORDER BY id DESC limit 1" ;

      $qry_result = mysqli_query($con,$query);// or die(mysqli_error());
    // Insert a new row in the table for each person returned
       while($row = mysqli_fetch_array($qry_result)) {

         array_push($arr, [
           'lat'=>[$row['latitude']],
           'lng'=>[$row['longitude']],
           //'recs'=>$recs
         ]);
       }
      }   


$record= json_encode($arr);
echo $record;    
?>