create table Student(S# varchar(10),Sname varchar(10),Sage date,Ssex varchar(10));
create table Course(C# varchar(10),Cname varchar(10),T# varchar(10));
create table Teacher(T# varchar(10),Tname varchar(10));
create table SC(S# varchar(10),C# varchar(10),score decimal(18,1));有以上4个表,要求得到下面的数据:
统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比 除了最后的百分比,剩下的信息都能通过下面的sql语句获得:select m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end) as px,
count(1)
from Course m , sc n
where m.C# = n.C#
group by m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end)
order by m.C# , m.Cname , px
请教:如何修改上面的sql,以得到包括百分比在内的所有数据?
create table Course(C# varchar(10),Cname varchar(10),T# varchar(10));
create table Teacher(T# varchar(10),Tname varchar(10));
create table SC(S# varchar(10),C# varchar(10),score decimal(18,1));有以上4个表,要求得到下面的数据:
统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比 除了最后的百分比,剩下的信息都能通过下面的sql语句获得:select m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end) as px,
count(1)
from Course m , sc n
where m.C# = n.C#
group by m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end)
order by m.C# , m.Cname , px
请教:如何修改上面的sql,以得到包括百分比在内的所有数据?
解决方案 »
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然后直接用/做除法运算。。就是百分比
你把这个结果 乘以100后面的数都不要了 拼接个%符号就OK了
然后 /总数 就是百分比了
insert into Course values('01' , 'language' , '02');
insert into Course values('02' , 'maths' , '01');
insert into Course values('03' , 'english' , '03');SC:
insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);
1 01 language 70-85 4 66.67%
2 01 language 0-60 2 33.33%
3 02 maths 85-100 3 50%
4 02 maths 70-85 1 16.67%
5 02 maths 60-70 1 16.67%
6 02 maths 0-60 1 16.67%
7 03 english 85-100 2 33.33%
8 03 english 70-85 2 33.33%
9 03 english 0-60 2 33.33%
select t1.*,round(t1.num/t2.all_num*100,2) || '%' 百分比
from
(select m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end) as px,
count(1) num
from Course m , sc n
where m.C# = n.C#
group by m.C# , m.Cname , (
case when n.score >= 85 then '85-100'
when n.score >= 70 and n.score < 85 then '70-85'
when n.score >= 60 and n.score < 70 then '60-70'
else '0-60'
end)
order by m.C# , m.Cname , px) t1,(select m.C# , m.Cname ,
count(1) all_num
from Course m , sc n
where m.C# = n.C#
group by m.C# , m.Cname
order by m.C# , m.Cname) t2
where t1.c#=t2.c#