Because no examples are provided, and to alleviate any confusion as a result, the setAttribute() method is invoked like so:

setAttribute(ATTRIBUTE, OPTION);

So, if I wanted to ensure that the column names returned from a query were returned in the case the database driver returned them (rather than having them returned in all upper case [as is the default on some of the PDO extensions]), I would do the following:

<?php
// Create a new database connection.
$dbConnection = new PDO($dsn, $user, $pass);

// Set the case in which to return column_names.
$dbConnection->setAttribute(PDO::ATTR_CASE, PDO::CASE_NATURAL);
?>

Hope this helps some of you who learn by example (as is the case with me).

.Colin

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yeboahnanaosei at gmail dot com ¶

6 years ago

This is an update to a note I wrote earlier concerning how to set multiple attributes when you create you PDO connection string.

You can put all the attributes you want in an associative array and pass that array as the fourth parameter in your connection string. So it goes like this: 
<?php
$options = [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_CASE => PDO::CASE_NATURAL,
    PDO::ATTR_ORACLE_NULLS => PDO::NULL_EMPTY_STRING
];

// Now you create your connection string
try {
    // Then pass the options as the last parameter in the connection string
    $connection = new PDO("mysql:host=$host; dbname=$dbname", $user, $password, $options);

    // That's how you can set multiple attributes
} catch(PDOException $e) {
    die("Database connection failed: " . $e->getMessage());
}
?>

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gregory dot szorc at gmail dot com ¶

17 years ago

It is worth noting that not all attributes may be settable via setAttribute().  For example, PDO::MYSQL_ATTR_MAX_BUFFER_SIZE is only settable in PDO::__construct().  You must pass PDO::MYSQL_ATTR_MAX_BUFFER_SIZE as part of the optional 4th parameter to the constructor.  This is detailed in http://bugs.php.net/bug.php?id=38015

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yeboahnanaosei at gmail dot com ¶

7 years ago

Well, I have not seen it mentioned anywhere and thought its worth mentioning. It might help someone. If you are wondering whether you can set multiple attributes then the answer is yes.

You can do it like this:
try {
    $connection = new PDO("mysql:host=$host; dbname=$dbname", $user, $password);
    // You can begin setting all the attributes you want.
    $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    $connection->setAttribute(PDO::ATTR_CASE, PDO::CASE_NATURAL);
    $connection->setAttribute(PDO::ATTR_ORACLE_NULLS, PDO::NULL_EMPTY_STRING);

    // That's how you can set multiple attributes
}
catch(PDOException $e)
{
    die("Database connection failed: " . $e->getMessage());
}

I hope this helps somebody. :)

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Anonymous ¶

3 years ago

Note that contrary to most PDO methods, setAttribute does not throw a PDOException when it returns false.

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steve at websmithery dot co dot uk ¶

7 years ago

For PDO::ATTR_EMULATE_PREPARES, the manual states a boolean value is required. However, when getAttribute() is used to check this value, an integer (1 or 0) is returned rather than true or false.

This means that if you are checking a PDO object is configured as required then

<?php
        // Check emulate prepares is off
        if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) !== false) {
            /* do something */
        }
?>

will always 'do something', regardless.

Either

<?php
        // Check emulate prepares is off
        if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) != false) {
            /* do something */
        }
?>

or

<?php
        // Check emulate prepares is off
        if ($pdo->getAttribute(\PDO::ATTR_EMULATE_PREPARES) !== 0) {
            /* do something */
        }
?>

is needed instead.

Also worth noting that setAttribute() does, in fact, accept an integer value if you want to be consistent.

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antoyo ¶

13 years ago

There is also a way to specifie the default fetch mode :

<?php

$connection = new PDO($connection_string);

$connection->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_OBJ);

?>

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-1

david at datava dot com ¶

7 months ago

Note that in order for
\PDO::ATTR_TIMEOUT
to have any effect, you must set 

\PDO::ATTR_ERRMODE=>\PDO::ERRMODE_EXCEPTION.

If

\PDO::ATTR_ERRMODE=>\PDO::ERRMODE_WARNING

it doesn't appear to do anything.