Calculating the min, median and max in PostgreSQL

median_example.sql

-- Small example demonstrating to calculate the median without using an custom built aggregate function
select 
  min(score)
  -- percentile_cont is a function that returns a value corresponding to the specified fraction in the ordering,
  -- interpolating between adjacent input items if needed. By setting the fraction to 0.5, this essentially works
  -- as the median of the ordered set provided by the grouping.
  , percentile_cont(0.5) with group (order by score) AS median
  , max(score) 
from result;