How could I change this 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($sql); to mysqli _query($sql); ?**

<?PHP

//in my header file that is included on every page I have this
$DB["dbName"] = "emails";
$DB["host"] = "localhost";
$DB["user"] = "root";
$DB["pass"] = "";
$link = mysql_connect($DB['host'], $DB['user'], $DB['pass']) or die("<center>An Internal Error has Occured. Please report following error to the webmaster.<br><br>".mysql_error()."'</center>");
mysql_select_db($DB['dbName']);
// end header connection part

// function from a functions file that I run a mysql query through in any page.
function executeQuery($sql) {
    $result = mysql_query($sql);
    if (mysql_error()) {
     $error = '<BR><center><font size="+1" face="arial" color="red">An Internal Error has Occured.<BR> The error has been recorded for review</font></center><br>';
     if ($_SESSION['auto_id'] == 1) {
      $sql_formatted = highlight_string(stripslashes($sql), true);
      $error .= '<b>The MySQL Syntax Used</b><br>' . $sql_formatted . '<br><br><b>The MySQL Error Returned</b><br>' . mysql_error();
     }
     die($error);
    }
    return $result;
}

// example query ran on anypage of the site using executeQuery funtion
$sql='SELECT auto_id FROM friend_reg_user WHERE auto_id=' .$info['auto_id'];
$result_member=executequery($sql);
if($line_member=mysql_fetch_array($result_member)){
    extract($line_member);
} else {
    header("location: index.php");
    exit;
}
?>

Answer 1

I would tentatively recommend using PDO for your SQL access.

Then it is only a case of changing the driver and ensuring the SQL works on the new backend. In theory. Data migration is a different issue.

Abstract database access is great.

Answer 2

The first thing to do would probably be to replace every mysql_* function call with its equivalent mysqli_*, at least if you are willing to use the procedural API -- which would be the easier way, considering you already have some code based on the mysql API, which is a procediral one.

To help with that, the The MySQLi Extension Function Summary is definitly something that will prove helpful.

For instance :

• mysql_connect will be replaced by mysqli_connect
• mysql_error will be replaced by mysqli_error and/or mysqli_connect_error, depending on the context
• mysql_query will be replaced by mysqli_query
• and so on

Note that, for some functions, you may need to check the parameters carefully : maybe there are some differences here and there -- but not that many, I'd say : both mysql and mysqli are based on the same library (libmysql ; at least for PHP <= 5.2)

For instance :

• with mysql, you have to use the mysql_select_db once connected, to indicate on which DB you want to do your queries
• mysqli, on the other side, allows you to specify that database name as the fourth parameter to mysqli_connect.
• still, there is also a mysqli_select_db function that you can use, if you prefer.

Once you are done with that, try to execute the new version of your script... And check if everything works ; if not... Time for bug hunting ;-)

Answer 3

if you want to keep the procedural programming, just add an "i" after mysql in every mysql_* function. otherwise check the manual for more details http://www.php.net/manual/en/book.mysqli.php

I do recommend you using PDO too. I use codeigniter to abstract my database access