select count(*) from authors where city=’beijin’.对于上一条语句，下面表述是正确的()
举一反三
- select au_id from authors where state=”ca” or state=”ks”. 下面哪一条语句与这一条语句执行效果相同？ A: select au_id from authors where statenot IN(“ca”,”ks”) B: select au_id from authors where state between ac and sk C: select au_id from authors where state not between ca and ks D: select au_id from authors where state IN(“ca”,”ks”)
- 检索选课人数少于4人的课程号。正确的SQL语句是( ) A: SELECT CNO FROM SC WHERE COUNT(*)<;4 B: SELECT CNO FROM SC GROUP BY CNO HAVING COUNT(*)<;4 C: SELECT DISTINCT CNO FROM SC ORDER BY CNO D: SELECT CNO FROM SC WHERE COUNT(CNO)<;4
- 补全语句：select vend_id,count(*) from products where prod_price>=10 group by vend_id ____ count(*)>=2;
- 下面哪一条语句是正确的() A: select from b B: select sno from a where sno 2000 C: select * from a order by sno where age>20 D: select * from B group by cno where cno>1
- 查询选修了数学课(课程号为2)的学生人数,可以使用的查询语句是: 。 A: SELECT MAX(*) FROM SC WHERE Cno = 2; B: SELECT AVG(Sno) FROM SC WHERE Cno = 2; C: SELECT COUNT(*) FROM SC WHERE Cno = 2; D: SELECT COUNT(Sname) FROM SC WHERE Cno = 2;