When Grade between 90 and 100 THEN Grade = '优'
When Grade between 80 and 89 THEN Grade = '良'
When Grade between 70 and 79 THEN Grade = '中'
When Grade between 60 and 69 THEN Grade = '及格'
Else Grade = '不及格'
End
C. Case
When Grade between 90 and 100 THEN '优'
When Grade between 80 and 89 THEN '良'
When Grade between 70 and 79 THEN '中'
When Grade between 60 and 69 THEN '及格'
Else '不及格'
End
D. Case Grade
When 90~100 THEN Grade = '优'
When 80~89 THEN Grade = '良'
When 70~79 THEN Grade = '中'
When 60~69 THEN Grade = '及格'
Else Grade = '不及格'
End
8．下述语句的功能是将两个查询结果合并为一个结果。其中正确的是 B
A．select sno,sname,sage from student where sdept = 'cs'
Order by sage
Union
select sno,sname,sage from student where sdept = 'is'
Order by sage
B．select sno,sname,sage from student where sdept = 'cs'
Union
select sno,sname,sage from student where sdept = 'is'
Order by sage
C．select sno,sname,sage from student where sdept = 'cs'
Union
select sno,sname from student where sdept = 'is'
Order by sage
D．select sno,sname,sage from student where sdept = 'cs'
Order by sage
Union
select sno,sname,sage from student where sdept = 'is'
9．下列SQL语句中，用于修改表数据的语句是 C
A．ALTER B．SELECT
C．UPDATE D．INSERT
10．设有Teachers表，该表的定义如下：
CREATE TABLE Teachers(