oracle数据库SQL题
1.有下表:
create table a
(
id number(10),PK
amt number(14,2),
type number(4)
);
create table b
(
id number(10), FK
name varchar2(20)
);
表A中的字段值:
-----------------------
|__ID__|__amt_|__type_|
|__1___|__20__|____2__|
|__2___|__30__|____3__|
|__3___|__50__|____5__|
|__4___|__70__|____7__|
|__5___|__53__|____53_|
表B中的字段值:
-----------------------
|__ID__|__name_|
|__1___|__aaa__|
|__2___|__bbb__|
|__3___|__ccc__|
|__4___|__ddd__|
|__5___|__fff__|
要求:连接查询出当type为2时查询amt的值与表B中对应的name值,字段重命名为(amt1),
当type为3时、为5时，查询出type为3的amt值加上type为5的amt值与表B中对应的name值，并将字段重命名为(amt2)；
当type为7时、为53时，查询出type为7的amt值加上type为53的amt值与表B中对应的name值，并将字段重命名为(amt3)；
(注:使用一条语句查询)
2.有下表:
create table studentsscore(
stu_id varchar2(50) null ,(学号)
kc varchar2(50) null, (课程)
score decimal(18,1) null (成绩)
)
取每科成绩前两名的学生信息并按课程号和成绩排序(注:使用一条语句(要求写出三种查询方法))
3.有下表:(stu)
-----------------------
|__ID__|_name_|_score_|
|__1___|__aa__|__80 __|
|__2___|__bb__|___90__|
|__3___|__cc__|___95__|
|__4___|__dd__|___70__|
|__5___|__ee__|___60_|
用一条语句输出,成绩在90分以上评为'EXCELLENT', 80-90分评为'GOOD',其他评为'SOSO'
以上三题是,曾经在工作遇到SQL问题,现在已经解决,想把结果与大家一起分享!如有不足之路,欢迎讨论!
答案:
1>select b.name,sum(decode(a.type,2,amt,0)) amt1,
sum(decode(a.type,3,amt,0))+sum(decode(a.type,5,amt,0)) amt2,
sum(decode(a.type,7,amt,0))+sum(decode(a.type,53,amt,0)) amt3
from A,B where a.id=b.id group by b.name,
sum(decode(a.type,3,amt,0))+sum(decode(a.type,5,amt,0)) amt2,
sum(decode(a.type,7,amt,0))+sum(decode(a.type,53,amt,0)) amt3
from A,B where a.id=b.id group by b.name,
2>方法一:
select kc,stu_id,score from student as t1 where (select count(*) from studnet as t2 where t1.kc=t2.kc and t1.score>t2.score)
select kc,stu_id,score from student as t1 where (select count(*) from studnet as t2 where t1.kc=t2.kc and t1.score>t2.score)
<2 order by kc,score desc
方法二:
select a.* from student as a where a.stu_id in ( select top 2 stu_id from student where kc=a.kc order by score dese)
select a.* from student as a where a.stu_id in ( select top 2 stu_id from student where kc=a.kc order by score dese)
方法三:
select kc, max(score) from student group by kc
union
select kc,max(score) from student as a where score not in(select max(score) from student b where a.kc = b.kc group by kc)
select kc, max(score) from student group by kc
union
select kc,max(score) from student as a where score not in(select max(score) from student b where a.kc = b.kc group by kc)
group by kc.
3> select id,name,score
case when score>90 then 'excellent'
when score>80 and score<=90 then 'good'
else 'soso'
end as 奖评
from stu
3> select id,name,score
case when score>90 then 'excellent'
when score>80 and score<=90 then 'good'
else 'soso'
end as 奖评
from stu