SQL query to group by age range from date created - sql

Question

I want to get statistics with sql query. My table is like this:
ID MATERIAL CREATEDATE DEPARTMENT
1 M1 10.10.1980 D1
2 M2 11.02.1970 D2
2 M3 18.04.1971 D3
.....................
.....................
.....................
How can I get a range of data count like this
DEPARTMENT AGE<10 10<AGE<20 20<AGE
D1 24 123 324
D2 24 123 324

Answer 1

Assuming that CREATEDATE is a date column, in PostgreSQL you can use the AGE function:
select DEPARTMENT, age(CREATEDATE) as AGE
from Materials
and with date_part you can get the age in years. To show the data in the format that you want, you could use this GROUP BY query:
select
DEPARTMENT,
sum(case when date_part('year', age(CREATEDATE))<10 then 1 end) as "age<10",
sum(case when date_part('year', age(CREATEDATE))>=10 and date_part('year', age(CREATEDATE))<20 then 1 end) as "10<age<20",
sum(case when date_part('year', age(CREATEDATE))>=20 then 1 end) as "20<age"
from
Materials
group by
DEPARTMENT
which can be simplified as:
with mat_age as (
select DEPARTMENT, date_part('year', age(CREATEDATE)) as mage
from Materials
)
select
DEPARTMENT,
sum(case when mage<10 then 1 end) as "age<10",
sum(case when mage>=10 and mage<20 then 1 end) as "10<age<20",
sum(case when mage>=20 then 1 end) as "20<age"
from
mat_age
group by
DEPARTMENT;
if you are using PostgreSQL 9.4 you can use FILTER:
with mat_age as (
select DEPARTMENT, date_part('year', age(CREATEDATE)) as mage
from Materials
)
select
DEPARTMENT,
count(*) filter (where mage<10) as "age<10",
count(*) filter (where mage>=10 and mage<20) as "10<age<20",
count(*) filter (where mage>=20) as "20<age"
from
mat_age
group by
DEPARTMENT;

Answer 2

The following solution assumes that your CREATEDATE column exists as some sort of valid Postgres date type. If this be not the case, and it is being stored as text, you will first have to convert it to date in order for the query to work.
SELECT DEPARTMENT,
SUM(CASE WHEN DATEDIFF(year, CREATEDATE, now()::date) < 10 THEN 1 ELSE 0 END) AS "AGE<10",
SUM(CASE WHEN DATEDIFF(year, CREATEDATE, now()::date) >= 10 AND
DATEDIFF(year, CREATEDATE, now()::date) < 20 THEN 1 ELSE 0 END) AS "10<AGE<20",
SUM(CASE WHEN DATEDIFF(year, CREATEDATE, now()::date) >= 20 THEN 1 ELSE 0 END) AS "20<AGE"
FROM Materials
GROUP BY DEPARTMENT

Answer 3

You can use extract(year FROM age(createdate)) to get the exact age
i.e
select extract(year FROM age(timestamp '01-01-1989')) age
will give you
Result:
age
---
27
so you can use following select statement to get your desired output:
SELECT dept
,sum(CASE WHEN age < 10THEN 1 END) "age<10"
,sum(CASE WHEN age >= 10 AND age < 20 THEN 1 END) "10<age<20"
,sum(CASE WHEN age >= 20 THEN 1 END) "20<age"
FROM (
SELECT dept,extract(year FROM age(crdate)) age
FROM dt
) t
GROUP BY dept
If you don't want to use a sub select use this.
SELECT dept
,sum(CASE WHEN extract(year FROM age(crdate)) < 10THEN 1 END) "age<10"
,sum(CASE WHEN extract(year FROM age(crdate)) >= 10 AND extract(year FROM age(crdate)) < 20 THEN 1 END) "10<age<20"
,sum(CASE WHEN extract(year FROM age(crdate)) >= 20 THEN 1 END) "20<age"
FROM dt
GROUP BY dept