北大青 7E 男 聚合函数-1 SUM SELECT SUM(ytd sales)FROM titles WHErEtype=business SELECT SUM(td sales), Price FROM titles WHERE type="business' X AVG SELECTAVG( SCore)AS平均成绩 From Score WherE score >=60 ACCP V4.0ACCP V4.0 9 聚合函数-1 SUM AVG SELECT SUM(ytd_sales) FROM titles WHERE type = 'business' SELECT SUM(ytd_sales) ,Price FROM titles WHERE type = 'business' × SELECT AVG(SCore) AS 平均成绩 From Score WHERE Score >=60