SQL placeholder replacement

pdo-print.php

<?php

# for when you need to print out a PDO prepared statement or similar with ":symbol" style placeholders

function pdoprint($sql, $values)
{
    return preg_replace_callback(
        '/:[^\s;)]*/',
        function ($matches) use (&$values) {
            return "'" . array_shift($values) . "'";
        },
        $sql
    );
}

$sql = "SELECT * FROM users WHERE username = :name AND last_login > :last_login";
$values = array(":name" => "jsmith2", ":last_login" => "2012-08-05");

echo pdoprint($sql, $values); # => SELECT * FROM users WHERE username = jsmith2 AND last_login > 2012-08-05
echo "<br><br>";

# You could also run the $placeholders array through a flattener to account for single-level lists

function flatten($values)
{
    return array_map(function ($v) {
        if (is_array($v)) { 
            $v = implode("','", $v); 
        }
        return $v;
    }, $values);
}

$sql = "SELECT * FROM users WHERE role IN (:roles) AND first_name = :first_name";
$values = array(":roles" => array("admin", "contributor"), ":first_name" => "leslie");

echo pdoprint($sql, flatten($values)); # => SELECT * FROM users WHERE role IN ('admin','contributor') AND first_name = 'leslie'