Asked  2 Years ago    Answers:  5   Viewed   108 times

What are the technical reasons for why one shouldn't use mysql_* functions? (e.g. mysql_query(), mysql_connect() or mysql_real_escape_string())?

Why should I use something else even if they work on my site?

If they don't work on my site, why do I get errors like

Warning: mysql_connect(): No such file or directory



The MySQL extension:

  • Is not under active development
  • Is officially deprecated as of PHP 5.5 (released June 2013).
  • Has been removed entirely as of PHP 7.0 (released December 2015)
    • This means that as of 31 Dec 2018 it does not exist in any supported version of PHP. If you are using a version of PHP which supports it, you are using a version which doesn't get security problems fixed.
  • Lacks an OO interface
  • Doesn't support:
    • Non-blocking, asynchronous queries
    • Prepared statements or parameterized queries
    • Stored procedures
    • Multiple Statements
    • Transactions
    • The "new" password authentication method (on by default in MySQL 5.6; required in 5.7)
    • Any of the new functionality in MySQL 5.1 or later

Since it is deprecated, using it makes your code less future proof.

Lack of support for prepared statements is particularly important as they provide a clearer, less error-prone method of escaping and quoting external data than manually escaping it with a separate function call.

See the comparison of SQL extensions.

Sunday, September 18, 2022

Why not just do this...

define('PERMISSION_READ', 1);
define('PERMISSION_ADD',  2);

//run function
// this value would be pulled from a user's setting mysql table
$_ARR_permission = 5;

if($_ARR_permission & PERMISSION_READ) {
    echo 'Access granted.';
}else {
    echo 'Access denied.';

You can also create lots of arbitrary combinations of permissions if you use bits...

$read_only = PERMISSION_READ;

//manipulating permissions is easy...
$myrights = PERMISSION_READ;
$myrights |= PERMISSION_UPDATE;    // add Update permission to my rights
Sunday, August 21, 2022

Exceptions allow you to distinguish between different types of errors, and is also great for routing. For example...

class Application
    public function run()
        try {
            // Start her up!!
        } catch (Exception $e) {
            // If Ajax request, send back status and message
            if ($this->getRequest()->isAjax()) {
                return Application_Json::encode(array(
                    'status' => 'error',
                    'msg'    => $e->getMessage());

            // ...otherwise, just throw error
            throw $e;

The thrown exception can then be handled by a custom error handler.

Since PHP is a loosely typed language, you might need to ensure that only strings are passed as arguments to a class method. For example...

class StringsOnly
    public function onlyPassStringToThisMethod($string)
        if (!is_string($string)) {
            throw new InvalidArgumentException('$string is definitely not a string');

        // Cool string manipulation...

        return $this;

...or if you need to handle different types of exceptions in different ways.

class DifferentExceptionsForDifferentFolks
    public function catchMeIfYouCan()
        try {
        } catch (CantFlyForFreeException $e) {
            return 'Sorry, you can't fly for free dude. It just don't work that way!';
        } catch (DbException $e) {
            // Get DB debug info
            return 'Could not access database. What did you mess up this time?';
        } catch (Exception $e) {
            return 'I catch all exceptions for which you did not account!';

If using transactions in something like Zend Framework:

class CreditCardController extends Zend_Controller_Action
    public function buyforgirlfriendAction()
        try {

            $this->insertGift($giftName, $giftPrice, $giftWowFactor);

        } catch (Exception $e) {
            // Error encountered, rollback changes

            // Re-throw exception, allow ErrorController forward
            throw $e;
Tuesday, September 13, 2022

you can't print the result from mysqli_query, it is mysqli_resource and for dumping the error you need to change mysql_error() to mysqli_error()

$username = "bob";
$db = mysqli_connect("localhost", "username", "password", "user_data");
$sql1 = "select id from user_information where username='$username'";
$result = mysqli_query($db, $sql1) or die(mysqli_error());
while ($row = mysqli_fetch_array($result, MYSQLI_ASSOC)) { 
    echo $row['id'].'<br>'; 
Sunday, September 25, 2022

yo need create the user "pma" in mysql or change this lines(user and password for mysql):

/* User for advanced features */
$cfg['Servers'][$i]['controluser'] = 'pma'; 
$cfg['Servers'][$i]['controlpass'] = '';

Linux: /etc/phpmyadmin/

Sunday, August 14, 2022
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