public function delete()
{
$queryBuilder = new QueryBuilder('delete');
$queryBuilder->setFrom($this->getTableName());
foreach ($this->columns as $column) {
$column->onDelete($queryBuilder);
}
$sql = $queryBuilder->prepare();
DB::post($sql);
// unset all columns
foreach ($this->columns as $key => $row) {
unset($this->columns[$key]);
}
$this->columns = [];
}
