&lt;strong&gt;Er zat een fout in je SQL query!&lt;/strong&gt;&lt;br /&gt;You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'AND link.item_id = item.id 
                        AND item.product_group_id =' at line 9&lt;br /&gt;Query: &lt;br /&gt;&lt;i&gt;SELECT 
                    productgroup.*
                    FROM
                        ws_ridder_item_year_link as link
                        ,ws_ridder_item as item
                        ,ws_ridder_productgroup as productgroup
                    WHERE 
                        link.year_id =  
                        AND link.item_id = item.id 
                        AND item.product_group_id = productgroup.id 
                    GROUP BY
                        productgroup.`name`
                    &lt;/i&gt;&lt;br /&gt;&lt;br /&gt;