PHP: Can not use global variable in function to connect mysqli

Question

I've been searching stack to get my answer, but nothing fixed my problem. So here's my shot:

$conn = mysqli_connect('localhost', 'username', 'pass', 'db');
function GetArticle() {
  global $conn;
  $sql = "sql query";
  $getresult = mysqli_query($conn, $sql);
  ..
}

This doesn't seem to work. If I put $conn inside the function, it works fine.

Any ideas?

How'd you know the $conn = assignment actually resided in the global scope? — mario
– mario, Commented Apr 29, 2015 at 19:20
Hey mario, i've tried to use a simple variable and return it by the function with the global, worked fine. only the database connection wont work — Schteven
– Schteven, Commented Apr 29, 2015 at 19:22
Going off of @AbraCadaver the best thing would be to put your connection code in a separate file and include that connection file in future files( which connect to the a db ) — Worldgorger
– Worldgorger, Commented Apr 29, 2015 at 19:34
Try to get error with mysqli_connect_error() or mysqli_error(). Maybe you closed connection somewhere above or did not use mysqli_free_result() in some of your previous queries. — Sergiy T.
– Sergiy T., Commented Apr 29, 2015 at 21:36

Don't Panic · Accepted Answer · 2015-04-29 20:53:11Z

2

I don't know your exact situation, but in general I do not see the benefit to using $conn as global. Your function depends on a mysqli connection in order to work, so just make the connection a function parameter.

function GetArticle($conn) {
  $sql = "sql query";
  $getresult = mysqli_query($conn, $sql);
  ..
}

Then after you have established your connection, you can call the function with your connection object as its argument.

$conn = mysqli_connect('localhost', 'username', 'pass', 'db');
$article = GetArticle($conn);

I think this is a more manageable approach than trying to keep track of whether $conn is available in global scope before calling the function.

answered Apr 29, 2015 at 20:53

Don't Panic

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2 Comments

Schteven Over a year ago

it's that i have all my functions in one php file. but anyway, i fixed it by using mysql instead mysqli

Don't Panic Over a year ago

I remember once in an apartment I was renting, I asked the management to fix one of the bedroom doors that was hung at a slight angle, which prevented it from closing properly and left a sizable gap above the top corner. The maintenance guy fixed it by sawing off the bottom corner of the door.

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