Pimcore\Model\Element\Tag\Dao::batchAssignTagsToElement PHP Method

    public function batchAssignTagsToElement($cType, array $cIds, array $tagIds, $replace)
    {
        if ($replace) {
            $this->db->delete("tags_assignment", "ctype = " . $this->db->quote($cType) . " AND cid IN (" . implode(",", $cIds) . ")");
        }
        foreach ($tagIds as $tagId) {
            foreach ($cIds as $cId) {
                $this->doAddTagToElement($tagId, $cType, $cId);
            }
        }
    }