/**
* Decrement a column's value by a given amount.
*
* @param string $column
* @param int $amount
* @param array $extra
* @return \PDOStatement
*/
public function decrement($column, $amount = 1, array $extra = array())
{
$wrapped = $this->grammar->wrap($column);
$columns = array_merge(array($column => $this->raw("{$wrapped} - {$amount}")), $extra);
return $this->update($columns);
}
