我必须使用3张桌子
1. tbl_school_info
school_id school_name
1 St. Joseph
2 White Cross
2. tbl_student_info
student_id school_id student_name student_gender
1 1 maria liejal F
2 1 eerika carthy F
3 1 heron M
4 2 Glenn hui M
5 2 joseph M
6 2 christii F
7 2 hina moggy F
3. tbl_student_marks
marks_id school_id student_id scored_percentage
1 1 1 78
2 1 2 79
3 1 3 20
4 2 4 65
5 2 5 78
6 2 6 84
7 2 7 83
我需要的结果是每所学校的男生,女生和总学生人数,男女生及格率和得分最高的男女生百分比。结果将像这样::
school_name || male_stud_cnt || female_stud_cnt || passed_male_cnt || passed_female_cnt || top_percentage_male ||top_percentage_female
St. Joseph 1 2 0 2 20 79
White Cross 2 2 2 2 78 84
分数低于35%的学生考试不及格。如何编写查询以获得此结果?在MS SQL Server中使用SQL查询能否获得这样的结果?我无法计数,如何编写这样的查询?
答案 0 :(得分:1)
您可以尝试在表达式出现时使用常规聚合
with cte as
(
select school_name,a.student_id,student_gender,scored_percentage from
tbl_student_marks a inner join tbl_student_info b
on a.student_id=b.student_id
inner join tbl_school_info c on a.school_id=b.school_id
)
select school_name,
count(case when student_gender='M' then student_id end) as male_stud_cnt,
count(case when student_gender='F' then student_id end) as female_stud_cnt,
count(case when student_gender='M' and scored_percentage>35 then student_id end) as passed_male_cnt,
count(case when student_gender='F' and scored_percentage>35 then student_id end) as passed_female_cnt,
max(case when student_gender='M' then scored_percentage end) as top_percentage_male,
max(case when student_gender='F' then scored_percentage end) as top_percentage_female
from cte
group by school_name