Question

I have a small website that I wanted to switch over to the mysqli_* functions, and after reading up a lot on it I decided to do the switch by doing a replace-all mysql_ with mysqli_ — I then went through and verified that everything changed correctly…

Now, the mysqli_connect() works – (I get a valid resource connection back from it) but further down the PHP script I have a mysqli_query function that is returning NULL no matter what I put in as the SQL.

Any thoughts what could be happening?

The relevant code:

function connecti_database() {
  mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_DATABASE);
}

connecti_database();
$sql = 'SELECT * FROM table where id = 5';
$result = mysqli_query($sql);
var_dump($result); // this returns NULL every time

Answer 1

mysqli functions require two parameters, not one
…and a developer required to read documentation first.

function connecti_database() {
  global $mysqli;
  $mysqli = mysqli_connect(DB_HOST, DB_USER, DB_PASS, DB_DATABASE);
  mysqli_select_db($mysqli,DB_DATABASE);
}

connecti_database();
$sql = 'SELECT * FROM table where id = 5';
$result = mysqli_query($mysqli, $sql);

PHP Manual: http://php.net/manual/en/mysqli.query.php

mixed mysqli_query ( mysqli $link , string $query [, int $resultmode = MYSQLI_STORE_RESULT ] )