json_encode($data) = NULL

Question

Maybe you can help me. DB connection is ok (Connected successfully), the table name is correct (course_details), but echo json_encode($data); is NULL

<?php

   include "db.php";

   // Check connection
   if ($con->connect_error) {
      die("Connection failed: " . $conn->connect_error);
   } 
   echo "Connected successfully";

   $data=array();
   $q=mysqli_query($con,"'SET CHARACTER SET utf8' select * from 'course_details'");
   while ($row=mysqli_fetch_object($q)){
      $data[]=$row;
   }


   echo json_encode($data); 
   $conn->close();
?>

Thanks in advance!

Your query is going to fail. You have two statements that aren't separated, and one is surrounded by single quotes but should not be. You can't run two statements in a query without using `mysqli_multi_query`. And tables need to be surrounded by backticks, not quotes. This is why `$data` is empty. — aynber, Apr 05 '18 at 14:10

Lonergan6275 · Accepted Answer · 2018-04-05T14:36:59.400

-1

firstly I would suggest wrapping the query in a try catch block

secondly as is mentioned in the comments above you have 2 queries in in the string.

try{
    $q=mysqli_query($con,"select * from `course_details`");
    $data = [];
    while ($row=mysqli_fetch_object($q)){
        array_push($data, $row);
    }
    echo json_encode($data); 
} catch (Exception $e) {
    echo "It reached the catch block " . $e->getMessage();
}

edited Apr 05 '18 at 14:36

answered Apr 05 '18 at 14:26

Lonergan6275

1,938
6
32
63

Your query will still fail because of the single quotes around the table. And since it would return null instead of throwing an exception, the OP should check for [mysqli errors](http://php.net/manual/en/mysqli.error.php). – aynber Apr 05 '18 at 14:33
@aynber whats the problem with wrapping the table name in single quotes? – Lonergan6275 Apr 05 '18 at 14:34
1

It will be treated as a string instead of a table or column name. http://stackoverflow.com/questions/11321491/when-to-use-single-quotes-double-quotes-and-backticks-in-mysql – aynber Apr 05 '18 at 14:35

json_encode($data) = NULL

1 Answers1