PHP Function Accessing Database Connection

Question

How do I allow a function to access a database connection without using GLOBAL?

config.php

 DEFINE ('DB_HOSTNAME', 'hostname');
 DEFINE ('DB_DATABASE', 'database');
 DEFINE ('DB_USERNAME', 'username');
 DEFINE ('DB_PASSWORD', 'password');

 $dbc = mysqli_connect(DB_HOSTNAME, DB_USERNAME, DB_PASSWORD, DB_DATABASE);

 if(!$dbc) die("Unable to connect to MySQL: " . mysqli_error($dbc));

functions.php

 function something()
 {
 $info = mysqli_query($dbc, "SELECT info FROM text") or die("Error: ".mysqli_error($dbc));
 }

The above gives me the following error: mysqli_query() expects parameter 1 to be mysqli, null given in

Let your ART OF DEBUGGING be groomed, Dont put such errors on Stack man — Jatin Dhoot
– Jatin Dhoot, Commented Jul 20, 2011 at 9:25
The day you'll change you db to mysql, oracle or another one, you'll get stucked with your connection handler. You should use PDO instead. — hornetbzz
– hornetbzz, Commented Jul 20, 2011 at 9:44

KingCrunch · Accepted Answer · 2011-07-20 09:24:29Z

6

Use function parameters

function something ($dbc) {
  // your db code here
}

function arguments

edited Jul 20, 2011 at 9:24

answered Jul 20, 2011 at 9:13

KingCrunch

133k22 gold badges158 silver badges174 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

markerpower Over a year ago

That gives me the error: Missing argument 1 for something() and mysqli_query() expects parameter 1 to be mysqli, null given in

KingCrunch Over a year ago

Of course you must call the function with the connection handler as the argument!

Mike · Accepted Answer · 2011-07-20 09:30:40Z

Either pass the database handle to your function, as @KingCrunch and others have said, or call a function that returns the handle:

In config.php:

function get_dbc() {
    $dbc = mysqli_connect(DB_HOSTNAME, DB_USERNAME, DB_PASSWORD, DB_DATABASE);
    if(!$dbc) die("Unable to connect to MySQL: " . mysqli_error($dbc));
    return $dbc;
}

In functions.php:

require_once('config.php');

function something()
{
    $dbc = get_dbc();
    $info = mysqli_query($dbc, "SELECT info FROM text") or die("Error: ".mysqli_error($dbc));
}

You may wish to look at The mysqli Extension and Persistent Connections for details on how you can prevent the connection from being re-established on each call to get_dbc(). There are alternative approaches to this, such as creating a singleton class for your database connection.

Rakesh Sankar · Accepted Answer · 2011-07-20 09:27:59Z

1

There are two ways one is by passing arguments and the other by using function closure like @Ondrej said. But I wonder both of these require you to modify the code if that is the case, then I would suggest you to use global keyword.

You can use global keyword to get the scope of variable $dbc

Try this..

function something()
{
   global $dbc;
   $info = mysqli_query($dbc, "SELECT info FROM text") or die("Error: ".mysqli_error($dbc));
}

(OR)

Try this...

function something()
{
    $dbc = func_get_arg(0);
     $info = mysqli_query($dbc, "SELECT info FROM text") or die("Error: ".mysqli_error($dbc));
}

& do this ....

$query = something($dbc);

edited Jul 20, 2011 at 9:27

answered Jul 20, 2011 at 9:16

Rakesh Sankar

9,4255 gold badges45 silver badges67 bronze badges

1 Comment

Ondrej Slinták Over a year ago

He doesn't want to use global.

Hassan Saeed · Accepted Answer · 2016-12-18 10:51:31Z

1

its so simple just pass your $conn variable into another calling function(instead of making new connection) like

yourpage.php

$conn = new mysqli($servername, $username, $password, $dbname);
someFunction ($conn)//you can add other parameters if you like 

function someFunction ($conn) {
    $result = mysqli_query ($conn, "SELECT * FROM examples);
}

Note:This is not good practice to always make new connection for database access.so always make connection once and use it every where.(but if your requirement different and require multiples connections then you can make multiples connections)

answered Dec 18, 2016 at 10:51

Hassan Saeed

7,1701 gold badge43 silver badges38 bronze badges

Comments

Ondrej Slinták · Accepted Answer · 2011-07-20 09:16:43Z

0

There are more ways. You could use classic procedural style:

function something($dbc)

or anonymous function (if you use PHP5.3):

$fn = function() using ($dbc)

answered Jul 20, 2011 at 9:16

Ondrej Slinták

32.1k21 gold badges97 silver badges127 bronze badges

1 Comment

Ondrej Slinták Over a year ago

I just showed possibilities. And anonymous function is a possibility in this case - he can use using.

Collectives™ on Stack Overflow

PHP Function Accessing Database Connection

5 Answers 5

2 Comments

Comments

1 Comment

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

2 Comments

Comments

1 Comment

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related