How to change mysql to mysqli?

Question

Based on this code below I use for regular mysql, how could I convert it to use mysqli?

Is it as simple as changing mysql_query($sql); to

Answer 1

Here is a complete tutorial how to make it quickly if you need to make worgking again a website after PHP upgrade. I used it after upgrading hosting for my customers from 5.4 (OMG!!!) to 7.x PHP version.

This is a workaround and it is better to rewrite all code using PDO or mysqli Class.

1. Connection definition

First of all, you need to put the connection to a new variable $link or $con, or whatever you want.

Example

Change the connection from :

@mysql_connect($host, $username, $password) or die("Error message...");
@mysql_select_db($db);

or

@mysql_connect($host, $username, $password, $db) or die("Error message...");

to:

$con = mysqli_connect($host, $username, $password, $db) or die("Error message...");

2. mysql_* modification

With Notepad++ I use "Find in files" (Ctrl + Shift + f) :

in the following order I choose "Replace in Files" :

1. mysql_query( -> mysqli_query($con,

2. mysql_error() -> mysqli_error($con)

3. mysql_close() -> mysqli_close($con)

4. mysql_insert_id() -> mysqli_insert_id($con)

5. mysql_real_escape_string( -> mysqli_real_escape_string($con,

6. mysql_ -> mysqli_

3. adjustments

if you get errors it is maybe because your $con is not accessible from your functions.

You need to add a global $con; in all your functions, for example :

function my_function(...) {
    global $con;
    ...
}

In SQL class, you will put connection to $this->con instead of $con. and replace it in each functions call (for example : mysqli_query($con, $query);)