2
爲了簡化這個問題，我要提前道歉（我聽說傑夫的播客和他擔心問題的質量會「下降」），但我是卡住。我正在使用AquaData來打我的Informix數據庫。 MS SQL和Informix SQL之間有些古怪的細微差別。無論如何，我試圖做一個簡單的嵌套表達式，它恨我。Informix SQL語法 - 巢數，總和，回合
select
score,
count(*) students,
count(finished) finished,
count(finished)/count(*)students
-- round((count(finished)/count(*)students),2)
from now_calc
group by score
order by score
與簡單的除法表達的行返回的人誰完成，這正是我想要的。我只是需要四捨五入至2位結果的百分比。註釋行（ - ）不起作用。我試過了我可能想到的每一個變化。
*我並不想在
我很抱歉，我應該提到，now_calc是一個臨時表，同時用線5 & 6和字段名實際上是「學生「和」完成「。我讓他們這樣命名，因爲我要將這些結果直接吐到Excel中，並且我希望字段名稱加倍作爲列標題。所以，我理解你說的話，並此基礎上，我把它通過刪除（*）這樣的工作：
select
score,
count(students) students,
count(finished) finished,
round((count(finished)/count(students) * 100),2) perc
from now_calc
group by score
order by score
我在內的整個查詢 - 這可能更有意義，任何人看着這個。從學習的角度來看，重要的是要注意計數在「已完成」字段工作的唯一原因是由於Case語句使值爲1或null，這取決於對Case語句的評估。如果不存在該案例陳述，則計數「完成」將產生與計算「學生」完全相同的結果。
--count of cohort members and total count of all students (for reference)
select
cohort_yr,
count (*) id,
(select count (*) id from prog_enr_rec where cohort_yr is not null and prog = 'UNDG' and cohort_yr >=1998) grand
from prog_enr_rec
where cohort_yr is not null
and prog = 'UNDG'
and cohort_yr >=1998
group by cohort_yr
order by cohort_yr;
--cohort members from all years for population
select
id,
cohort_yr,
cl,
enr_date,
prog
from prog_enr_rec
where cohort_yr is not null
and prog = 'UNDG'
and cohort_yr >=1998
order by cohort_yr
into temp pop with no log;
--which in population are still attending (726)
select
pop.id,
'Y' fin
from pop, stu_acad_rec
where pop.id = stu_acad_rec.id
and pop.prog = stu_acad_rec.prog
and sess = 'FA'
and yr = 2008
and reg_hrs > 0
and stu_acad_rec.cl[1,1] <> 'P'
into temp att with no log;
--which in population graduated with either A or B deg (702)
select
pop.id,
'Y' fin
from pop, ed_rec
where pop.id = ed_rec.id
and pop.prog = ed_rec.prog
and ed_rec.sch_id = 10
and (ed_rec.deg_earn[1,1] = 'B'
or (ed_rec.deg_earn[1,1] = 'A'
and pop.id not in (select pop.id
from pop, ed_rec
where pop.id = ed_rec.id
and pop.prog = ed_rec.prog
and ed_rec.deg_earn[1,1] = 'B'
and ed_rec.sch_id = 10)))
into temp grad with no log;
--combine all those that either graduated or are still attending
select * from att
union
select * from grad
into temp all_fin with no log;
--ACT scores for all students in population who have a score (inner join to eliminate null values)
--score > 50 eliminates people who have data entry errors - SAT scores in ACT field
--2270
select
pop.id,
max (exam_rec.score5) score
from pop, exam_rec
where pop.id = exam_rec.id
and ctgry = 'ACT'
and score5 > 0
and score5 < 50
group by pop.id
into temp pop_score with no log;
select
pop.id students,
Case when all_fin.fin = 'Y' then 1 else null end finished,
pop_score.score
from pop, pop_score, outer all_fin
where pop.id = all_fin.id
and pop.id = pop_score.id
into temp now_calc with no log;
select
score,
count(students) students,
count(finished) finished,
round((count(finished)/count(students) * 100),2) perc
from now_calc
group by score
order by score
謝謝！