是否有一个 sql 查询来计算特定年份的人数，知道每个人的出生日期和死亡日期？

Question

我有一个 table 显示姓名、出生日期和死亡日期 (1900-2000)。我需要知道某个时期每年的人口数量，例如，1940年人口为23亿，1941年为24亿，1942年为22亿，以此类推，直到1950年。

我在 SAS Enterprise Guide 工作，代码看起来可能与正常代码略有不同 sql。至少我想看到这样的东西：

~ 人数 |年

2.300.000.000 |1940 2.400.000.000 |1941 .....................

select
count(name),
from db
where bd<1jan1940 and dd>=1jan1940 and dd=<31dec1940
group by month

Answer 1

首先你要知道1899年底的初始人口，假设是20亿。然后加上每年的出生人数减去死亡人数。（您必须访问 table 两次才能执行此操作，一次用于出生，一次用于死亡。）使用 SUM OVER 获得运行总数。

我不确定您实际使用的是哪个 DBMS，但这是非常标准的 SQL:

select yr, 2000000000 + sum(births.cnt - deaths.cnt) over (order by yr)
from
(
  select extract(year from bd) as yr, count(*) as cnt 
  from db
  group by extract(year from bd)
) births
join
(
  select extract(year from dd) as yr, count(*) as cnt 
  from db
  group by extract(year from dd)
) deaths using (yr)
order by yr;

Answer 2

data dob_data;
do i = 1 to 10000;
    num = ceil(rand('UNIFORM',0,10));   
    dob = intnx('day','01JAN1899'd,ceil(rand('UNIFORM',1,36865)));
    select (num);
        when (1)  dod = intnx('day',dob,ceil(rand('UNIFORM',1,36865)));
        otherwise dod = .;
    end;
    output;
end;
format dob dod date9.;
drop num;
run;


data calendar;
    do i=0 to 100;
        year = 1900+i;
        soy = intnx('year','01JAN1900'd,i,'s');
        eoy = intnx('year','01JAN1900'd,i,'e');
        output;
    end;
    format soy eoy date9.;
run;


proc sql;
    create table pop as
    select year,
    sum(case when DOB < soy and coalesce(DOD,'31DEC2200'd) ge soy then 1 else 0 end) as Alive_At_Start,
    sum(case when DOB between soy and eoy then 1 else 0 end) as Born_During,
    sum(case when coalesce(DOD,'31DEC2200'd) between soy and eoy then -1 else 0 end) as Passed,
    sum(case when DOB le eoy and coalesce(DOD,'31DEC2200'd) > eoy then 1 else 0 end) as Alive_At_End
    from dob_data t1, calendar t2
    group by year;
quit;

是否有一个 sql 查询来计算特定年份的人数，知道每个人的出生日期和死亡日期？

Is there an sql query to count the number of people in a particular year, knowing the date of birth and the date of death of each person?

sql

proc-sql