SQL: PERCENTILE_CONT

Create a test table

create table tq84_perc_cont (
   grp    varchar(10),
   val    decimal(5,3)
);

Insert some values

insert into tq84_perc_cont values ('A',  5.1);
insert into tq84_perc_cont values ('A', 17.8);
insert into tq84_perc_cont values ('A',  5.3);
insert into tq84_perc_cont values ('A',  4.8);

insert into tq84_perc_cont values ('B', 15.2);
insert into tq84_perc_cont values ('B',  8.9);
insert into tq84_perc_cont values ('B',  6.3);
insert into tq84_perc_cont values ('B', 22.1);

Selecting the median

select
   grp,
   val,
   percentile_cont(0.5) within group (order by val) over (                ) median,
   percentile_cont(0.5) within group (order by val) over (partition by grp) median_grp
from
   tq84_perc_cont
;

Using the aggregate

select
   grp,
   percentile_cont(0.5) within group (order by val)  median
from
   tq84_perc_cont   
group by
   grp;

See also