同一列中的计数条件 [英] Count On Condition in same column
本文介绍了同一列中的计数条件的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
经过很多搜索后,我必须在这里向专家咨询...
After searching a lot, I have to ask experts here...
表1(出席)
att_id att_date class_id student_id att_status
1 07-11-2013 1 1 P
2 07-11-2013 1 2 L
3 07-11-2013 1 3 P
4 07-11-2013 1 4 P
5 08-11-2013 2 5 P
6 08-11-2013 2 6 P
7 08-11-2013 2 7 A
8 08-11-2013 2 8 P
9 09-11-2013 1 1 L
10 09-11-2013 1 2 P
11 09-11-2013 1 3 A
12 09-11-2013 1 4 P
13 09-11-2013 2 5 P
其中在att_status中P =存在,A =缺勤,L =离开。现在我想根据类ID 计算个别学生的现在,缺席和离开。
Where in att_status P=Present, A=Absence, L=Leave. Now I want to count individual student Present, Absent and Leave based on class id.
希望的结果
stu_id class_id Present Absent Leave
1 1 1 0 1
2 1 1 0 1
3 1 1 1 0
4 1 2 0 0
5 2 1 0 0
6 2 1 0 0
7 2 0 1 0
8 2 1 0 0
推荐答案
select student_id,
class_id,
sum(att_status='P') as present,
sum(att_status='A') as absent,
sum(att_status='L') as leave
from attendance
group by student_id, class_id
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