queries5.sql

ssd7 ex3 答案

 SELECT name,AVG(qty)
 FROM supplier4,purchase_order4,ordered4
 WHERE supplier4.supplier_id=ordered4.supplier_id AND
       purchase_order4.ponum=ordered4.ponum 
 GROUP BY supplier4.name
 HAVING AVG(qty)>(SELECT AVG(qty)
		  FROM purchase_order4);