/**
* Add a "WHERE" clause to the given query.
*
* @param \Database\Query\Builder $query
* @param string $key
* @param string $extraValue
* @return void
*/
protected function addWhere(QueryBuilder $query, $key, $extraValue)
{
if ($extraValue === 'NULL') {
$query->whereNull($key);
} elseif ($extraValue === 'NOT_NULL') {
$query->whereNotNull($key);
} else {
$query->where($key, $extraValue);
}
}
