Example migration

gistfile1.php

public function preUp(Schema $schema)
{
    parent::preUp($schema);

    $this->addSql("CREATE TABLE cdp_timeline_link (id INT AUTO_INCREMENT NOT NULL, timeline_id INT DEFAULT NULL, action_button_text VARCHAR(50) NOT NULL, action_button_link VARCHAR(1024) NOT NULL, INDEX IDX_4BF3B3F6EDBEDD37 (timeline_id), PRIMARY KEY(id)) DEFAULT CHARACTER SET utf8 COLLATE utf8_unicode_ci ENGINE = InnoDB");
    $this->addSql("ALTER TABLE cdp_timeline_link ADD CONSTRAINT FK_4BF3B3F6EDBEDD37 FOREIGN KEY (timeline_id) REFERENCES cdp_timeline (id) ON DELETE CASCADE");
}

public function up(Schema $schema)
{
    parent::up($schema);

    $sql = 'SELECT id, action_button_text, action_button_link FROM cdp_timeline';

    /* @var $stmt \Doctrine\DBAL\Statement */
    $stmt = $this->executeQuery($sql, array(), array(), false);

    $section = '';
    $title = '';

    $results = $stmt->fetchAll();

    if ($stmt->rowCount() > 0) {
        $row = $stmt->fetch();
        $keys = array_keys($row);

        $section = $row[$keys[0]];
        $title = $row[$keys[1]];
    }

    return array('section' => $section, 'title' => $title);
}

public function postUp(Schema $schema)
{
    parent::postUp($schema);

    $this->addSql("ALTER TABLE cdp_timeline DROP action_button_text, DROP action_button_link");
}