Hey guys I am stuck at a problem in MySQL, can you please help me.
我有一个表格可以对某些参数进行评级。现在我要做的是我想要显示一个表格，其中每个LocationID所有参数值都应该显示在一行中。
这是我的第一个名为interviewmaster的表，其中存储了记录
InterviewID InterviewDate IntervieweeID SourceID LocationID
1 2013-06-10 16:11:09 1 1 3
2 2013-06-10 16:12:19 2 2 2
3 2013-06-10 16:13:05 3 5 5
4 2013-06-10 16:13:46 4 4 6
5 2013-06-10 16:14:35 5 2 1
6 2013-06-10 16:15:26 6 3 7
7 2013-06-10 16:16:05 7 5 8
8 2013-06-10 16:16:51 8 1 4
9 2013-06-10 16:22:31 9 5 3
10 2013-06-11 08:51:20 10 1 1
我的第二张表是面试参数
ParameterID Parameter
1 The Welcome
2 Quality Of Service
3 Speed Of Service
4 Staff Attitude
5 Quality of food/beverage
6 Overall value for money
7 Ambience
8 Overall Experience
我的第三张表是采访
InterviewID parameterID Rating
1 1 5
1 2 4
1 3 5
1 4 4
1 5 5
1 6 4
1 7 5
2 1 5
2 2 5
2 3 5
2 4 5
2 5 5
2 6 4
2 7 5
3 1 4
3 2 3
3 3 4
3 4 3
3 5 4
3 6 3
3 7 4
4 1 2
4 2 2
4 3 2
4 4 2
4 5 2
4 6 2
4 7 2
现在我正在使用的查询是
select LocationID,
(CASE when ParameterID=1 then avg(interviewratings.Rating) else null end) as Welcome,
(CASE when ParameterID=2 then avg(interviewratings.Rating) else null end) as Service,
(CASE when ParameterID=3 then avg(interviewratings.Rating) else null end) as Speed,
(CASE when ParameterID=4 then avg(interviewratings.Rating) else null end) as Quality,
(CASE when ParameterID=5 then avg(interviewratings.Rating) else null end) as Overall,
(CASE when ParameterID=6 then avg(interviewratings.Rating) else null end) as Ambience,
(CASE when ParameterID=7 then avg(interviewratings.Rating) else null end) as Experience
from interviewratings join interviewmaster on
interviewratings.InterviewID=interviewmaster.InterviewID
group by ParameterID, LocationID
这将结果显示为
LocationID welcome source speed quality overall Ambiance experience
1 2.8333
2 3.0000
3 3.4000
4 2.5000
5 2.3333
6 2.8000
7 2.8182
8 4.0000
1 3.0000
2 2.5714
3 3.2000
4 3.3333
5 2.6667
6 2.8000
7 2.3636
8 4.3333
1 3.0000
2 2.5714
3 3.4000
4 2.8333
5 3.8889
6 2.8000
7 2.7273
8 3.3333
1 3.0000
2 4.2857
3 3.2000
4 3.5000
5 2.7778
6 2.8000
7 3.0000
8 3.0000
1 3.0000
2 2.8571
3 3.4000
4 2.8333
5 3.6667
6 2.8000
7 3.1818
8 2.6667
1 3.0000
2 2.4286
3 3.2000
4 2.8333
5 2.6667
6 3.6000
7 3.0909
8 3.0000
1 3.0000
2 2.8571
3 3.8000
4 2.5000
5 2.6667
6 2.8000
7 3.0909
8 3.3333
位置表是
LocationID Location
1 Seasonal Tastes
2 Daily Treats
3 Eest
4 Prego
5 Mix
6 Splash
7 Xiao chi
8 The Living Room
我希望我的数据像这样
Location Welcome Service Speed Quality Overall Ambience Experience
seasonal 2.8333 3.0000 3.0000 3.0000 3.0000 3.0000 3.0000
Daily treats 3.0000 2.5714 2.5714 4.2857 2.8571 2.4286 2.8571
Eest 3.4000 3.2000 3.4000 3.2000 3.4000 3.2000 3.8000
Prego 2.5000 3.3333 2.8333 3.5000 2.8333 2.8333 2.5000
Mix 2.3333 2.6667 3.8889 2.7778 3.6667 2.6667 2.6667
Splash 2.8000 2.8000 2.8000 2.8000 2.8000 3.6000 2.8000
Xiao chi 2.8182 2.3636 2.7273 3.0000 3.1818 3.0909 3.0909
The Living 4.0000 4.3333 3.3333 3.0000 2.6667 3.0000 3.3333
以及这8行中所有列的所有结果..你能告诉我怎么做吗？
答案 0 :(得分：1)
试试这个：
select
l.Location,
sum(CASE when r.ParameterID=1 then r.Rating else 0 end)/sum(CASE when r.ParameterID=1 then 1 else 0 end) as Welcome,
sum(CASE when r.ParameterID=2 then r.Rating else 0 end)/sum(CASE when r.ParameterID=2 then 1 else 0 end) as Service,
sum(CASE when r.ParameterID=3 then r.Rating else 0 end)/sum(CASE when r.ParameterID=3 then 1 else 0 end) as Speed,
sum(CASE when r.ParameterID=4 then r.Rating else 0 end)/sum(CASE when r.ParameterID=4 then 1 else 0 end) as Quality,
sum(CASE when r.ParameterID=5 then r.Rating else 0 end)/sum(CASE when r.ParameterID=5 then 1 else 0 end) as Overall,
sum(CASE when r.ParameterID=6 then r.Rating else 0 end)/sum(CASE when r.ParameterID=6 then 1 else 0 end) as Ambience,
sum(CASE when r.ParameterID=7 then r.Rating else 0 end)/sum(CASE when r.ParameterID=7 then 1 else 0 end) as Experience
from
interviewratings r
join interviewmaster m
on m.InterviewID = r.InterviewID
join Location l
on l.LocationID = m.LocationID
group by
m.LocationID
答案 1 :(得分：1)
尝试
SELECT l.Location,
AVG(CASE WHEN r.ParameterID=1 THEN r.Rating ELSE NULL END) Welcome,
AVG(CASE WHEN r.ParameterID=2 THEN r.Rating ELSE NULL END) Service,
AVG(CASE WHEN r.ParameterID=3 THEN r.Rating ELSE NULL END) Speed,
AVG(CASE WHEN r.ParameterID=4 THEN r.Rating ELSE NULL END) Quality,
AVG(CASE WHEN r.ParameterID=5 THEN r.Rating ELSE NULL END) Overall,
AVG(CASE WHEN r.ParameterID=6 THEN r.Rating ELSE NULL END) Ambience,
AVG(CASE WHEN r.ParameterID=7 THEN r.Rating ELSE NULL END) Experience
FROM interviewmaster i JOIN Location l
ON i.LocationID = l.LocationID JOIN interviewratings r
ON i.InterviewID = r.InterviewID
GROUP BY i.LocationID, l.Location
这是 SQLFiddle 演示