使用不同的表计算 SQL 查询中的中位数

Question

我必须计算（Oracle）某些人年龄的中位数，但要获得年龄我必须在不同的表中搜索，所以为其他问题提供的解决方案对我没有帮助。

我有 4 个表，我必须加入这些表才能获取所选人员的年龄，然后计算中位数。

我获取年龄的查询类似于：

select p.year_born from patient p
where p.id in (
select distinct md.patient_id
from main_data md, treatment t, patient p, consultation c
where 1 = 1
and t.md_id = md.id 
and md.type = 'SOME_TYPE'
and c.id = p.consultation_id
and md.deleted = 0
and t.deleted = 0
and md.completed = 1
and md.patient_id = p.id
and c.testconsultation = 0);

我如何计算人们出生年份的中位数？

Answer 1

试试这个查询：

WITH 
t1 as  (SELECT year_born FROM (select TO_NUMBER(p.year_born) year_born from patient p
       where p.id in (
       select distinct md.patient_id
       from main_data md, treatment t, patient p, consultation c
       where 1 = 1
       and t.md_id = md.id 
       and md.type = 'SOME_TYPE'
       and c.id = p.consultation_id
       and md.deleted = 0
       and MLP.deleted = 0
       and md.completed = 1
       and md.patient_id = p.id
       and c.testconsultation = 0)) order by year_born),
t2 as (SELECT mod(count(year_born),2) as mod_num,count(year_born) as num FROM t1),
t3 as (SELECT ROWNUM r,t1.* FROM t1),
t4 as (SELECT CASE WHEN mod_num = 1 then round(num/2) else -1 end as t4_num FROM t2)
SELECT CASE WHEN t4.t4_num = -1 then ((SELECT year_born FROM t3 where r = (t2.num/2)) +
(SELECT year_born FROM t3 where r = (t2.num/2) + 1)) / 2 ELSE (SELECT year_born FROM t3 where r = t4_num) end as final_num
FROM t4,t2;

Answer 2

答案很简单：

select median (2014 - p.year_born) from patient p
where p.id in (
select distinct md.patient_id
from main_data md, treatment t, patient p, consultation c
where 1 = 1
and t.md_id = md.id 
and md.type = 'SOME_TYPE'
and c.id = p.consultation_id
and md.deleted = 0
and t.deleted = 0
and md.completed = 1
and md.patient_id = p.id
and c.testconsultation = 0);

我应该在问之前阅读 Oracle 文档...