I have payment amounts like so - How do I divide records like this into quartiles. It doesn't have to be perfect. For example, the data in the question would transform like so - Ids 124049 and 2323 are given the same quartile because those payment values are close together. Answer you can use ntile function : db<>fiddle here

Quartiles in Postgres

I have payment amounts like so –

id      payment
13743   2090439.11
1750327 514457.45
124049  1583176.43
2323    948421.5
1106    2334.2

​x
 
id      payment13743   2090439.111750327 514457.45124049  1583176.432323    948421.51106    2334.2​

How do I divide records like this into quartiles. It doesn’t have to be perfect. For example, the data in the question would transform like so –

id      payment     Quartile
13743   2090439.11  Q4
1750327 514457.45   Q2
124049  1583176.43  Q3
2323    1232336.5   Q3
1106    2334.2      Q1

 
id      payment     Quartile13743   2090439.11  Q41750327 514457.45   Q2124049  1583176.43  Q32323    1232336.5   Q31106    2334.2      Q1​

Ids 124049 and 2323 are given the same quartile because those payment values are close together.

you can use ntile function :

select * , ntile(4) over (order by payment) as Quartile
from data

 
select * , ntile(4) over (order by payment) as Quartilefrom data​

db<>fiddle here