Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'p.o1' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by: SELECT p.o1,  p.o2, p.ID, p.pID, p.longID, p.sku, p.title, p.vattype, p.`description`, p.price, p.listprice,  p.area, p.pricetype, p.priceper, p.shippingexempt, p.category, p.categorylongID, p.saleitem, p.imageURL, p.manufacturername, p.productcategoryID, p.vatdefault, p.vatincluded, p.vatprice, SUM(p.weight) AS score, p.ratepercent FROM ((SELECT productcategory.ordernum AS o1,  product.ordernum AS o2, product.ID, product.ID AS pID, product.longID, product.sku, product.title, product.vattype, product.`description`, product.price, product.listprice, product.area, product.pricetype, product.priceper, product.shippingexempt, productcategory.title AS category, productcategory.longID AS categorylongID, product.saleitem, productvatrate.ratepercent, product.imageURL, productmanufacturer.manufacturername, product.productcategoryID, productcategory.vatdefault, productcategory.vatincluded, productcategory.vatprice, 2 AS weight FROM product LEFT JOIN productcategory ON (product.productcategoryID = productcategory.ID)  LEFT JOIN productinregion ON (productinregion.productID = product.ID) LEFT JOIN productmanufacturer ON (product.manufacturerID = productmanufacturer.ID) LEFT JOIN productincategory ON (product.ID = productincategory.productID)  LEFT JOIN productcategory AS altproductcategory ON (altproductcategory.ID = productincategory.categoryID) LEFT JOIN productvatrate ON (product.vattype = productvatrate.ID) WHERE product.statusID = 1 AND productcategory.accesslevel=0 AND productcategory.groupID = 0  AND ((productinregion.regionID IS NULL AND 3 = 1) OR (productinregion.regionID = 3)) AND (productcategory.statusID =1 OR productcategory.statusID IS NULL) AND product.manufacturerID = 3 GROUP BY pID ) UNION ALL (SELECT productcategory.ordernum AS o1,  product.ordernum AS o2, product.ID, product.ID AS pID, product.longID, product.sku, product.title, product.vattype, product.`description`, product.price, product.listprice, product.area, product.pricetype, product.priceper, product.shippingexempt, productcategory.title AS category, productcategory.longID AS categorylongID, product.saleitem, productvatrate.ratepercent, product.imageURL, productmanufacturer.manufacturername, product.productcategoryID, productcategory.vatdefault, productcategory.vatincluded, productcategory.vatprice, 1 AS weight FROM product LEFT JOIN productcategory ON (product.productcategoryID = productcategory.ID)  LEFT JOIN productinregion ON (productinregion.productID = product.ID) LEFT JOIN productmanufacturer ON (product.manufacturerID = productmanufacturer.ID) LEFT JOIN productincategory ON (product.ID = productincategory.productID)  LEFT JOIN productcategory AS altproductcategory ON (altproductcategory.ID = productincategory.categoryID) LEFT JOIN productvatrate ON (product.vattype = productvatrate.ID) WHERE product.statusID = 1 AND productcategory.accesslevel=0 AND productcategory.groupID = 0  AND ((productinregion.regionID IS NULL AND 3 = 1) OR (productinregion.regionID = 3)) AND (productcategory.statusID =1 OR productcategory.statusID IS NULL) AND product.manufacturerID = 3 GROUP BY pID ))  AS p GROUP BY pID  ORDER BY score DESC