Database connection - PDO

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Guys, in the course, we are manipulating database with PDO, but now in the connection part, appeared to me the MYSQL_ATTR_INIT_COMMAND and I don’t really understand what it’s for, I just know that the PDO instance asks for it in options. But what’s it for? What exactly does it do?

php database pdo

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In the official documentation:

PDO::MYSQL_ATTR_INIT_COMMAND (integer)

Command to run when connecting to Mysql server. It will be executed again when reconnecting.

Note that this constant can only be used in the driver_options array build a new database handler.

I mean, it’s a command mysql which will run only once every connection, as soon as you connect (or reconnect) to the server.

Example of use:

$db = new PDO('mysql:dbname=mydb;host=localhost;port=3306', $user, $pass, 
    array(PDO::MYSQL_ATTR_INIT_COMMAND =>  "SET NAMES 'UTF8'")
);

The command SET NAMES 'UTF8' will run once, whenever this new connection starts.

  • Okay, Ricardo, thank you! But I’m still having doubts! I know he will run once when he connects, but, what does he do? It only serves to set the database to UTF8, etc...? Or I run what I want there?

  • @Lucascarvalho you can run any valid command.

  • Got it. Thank you Ricardo!!

1

charset

In versions prior to PHP 5.3.6, this element was ignored from silent form. The same behavior may be partially replicated with PDO::MYSQL_ATTR_INIT_COMMAND option, as well as example below demonstrates.

** Setting Character set to UTF-8 before PHP 5.3.6**

<?php
    $dsn = 'mysql:host=localhost;dbname=testdb';
    $username = 'username';
    $password = 'password';
    $options = array(
        PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
    ); 

    $dbh = new PDO($dsn, $username, $password, $options);
?>

With the PDO::MYSQL_ATTR_INIT_COMMAND we set only one that concerns the charset used by MYSQL, which will be UTF8.

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