二、（每小题6分，共24分）】 1.CREATE TABLE S( SNo INT PRIMARY KEY, SN CHAR(30), SA INT, SD CHAR(20) 〉： 2.CREATE TABLE C CNo INT PRIMARY KEY, CN CHAR(20), CC INT }: 3.CREATE TABLE SC( SNo INT, CNo INT, G INT, PRIMARY KEY(SNo,CNo), FOREIGN KEY(SNo)REFERENCES S(SNo), FOREIGN KEY(CNo)REFERENCES C(CNo) }; 4. SELECT SNo,SUM(G) FROM SC GROUP BY SNo ORDER BY SUM(G)DESC,SNo 三、（每小题6分，共12分） 1. SELECT Cno,AVG(Grade) FROM SC,Course WHERE SC.Cno=Course.Cno AND Teacher LIKE%' GROUP BY Cno; 412二、(每小题 6分 ，共 24分) 1. CREATE TABLE St SNo INT PRIMARY KEY SN CHAR(30)， SA INT， SD CHAR(20) 2. CREATE TABLE C{ CNo INT PRIM ARY KEY CN CHAR(20) CC INT }; 3. CREATE TABLE SC{ SNo INT， CNo INT， GINT， PRIMARY KEY(SNo，CNo)， FOREIGN KEY(SNo) REFERENCES S(SNo) FOREIGN KEY(CNo) REFERENCES C(CNo) SELECT'SNo，SUM<G) FROM SC GROUP BY SNo ORDER BY SUM(G) DESC,SNo 三、(每小题 6分 ，共 12分) SELEC"I' Cno，AVG(Grade) FROM SC,Course WHERE SC. Cno=Course. Cno AND Teacher LIKE‘张% GROUP BY Cno; 412