数据库实战完全笔记综合练习（1）授课信息查询

    此实例在Oracle10g运行通过：

一、题目要求

教师的授课信息存放在SCHEDULE表中 ：

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二、分析解答

1.建表语句 

create table schedule
(
	teacherid number(1),
	weekday number(1),
	hascourse number(1)
);
--插入数据语句
insert into schedule values(1,2,1);
insert into schedule values(1,3,1);
insert into schedule values(2,1,2);
insert into schedule values(3,2,1);
insert into schedule values(1,2,1);
--提交语句
commit; 

select  teacherid,
case when  weekday=1 then 1 else 0 end MONDAY,
case when  weekday=2 then 1 else 0 end TUESDAY, 
case when  weekday=3 then 1 else 0 end WEDNESDAY,
case when  weekday=4 then 1 else 0 end THURSDAY,
case when  weekday=5 then 1 else 0 end FRIDAY
from SCHEDULE;

select  teacherid,
sum(case when  weekday=1 then 1 else 0 end) MONDAY,
sum(case when  weekday=2 then 1 else 0 end) TUESDAY,
sum(case when  weekday=3 then 1 else 0 end) WEDNESDAY,
sum(case when  weekday=4 then 1 else 0 end) THURSDAY,
sum(case when  weekday=5 then 1 else 0 end) FRIDAY
from SCHEDULE
group by teacherID;

select teacherid,
nvl ((SUM(decode(weekday, '1', 1))),0) as  MONDAY,
nvl ((SUM(decode(weekday, '2', 1))),0) as  TUESDAY,
nvl ((SUM(decode(weekday, '3', 1))),0) as  WEDNESDAY,
nvl ((SUM(decode(weekday, '4', 1))),0) as  THURSDAY,
nvl ((SUM(decode(weekday, '5', 1))),0) as  FRIDAY
from SCHEDULE
group by teacherid;

查询结果如下图：

数据库实战完全笔记综合练习（1）授课信息查询

原文：http://blog.csdn.net/sinat_26342009/article/details/45169233