Postgres 12

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create type ratio as (numerator bigint, denominator bigint);

create table my_ratios(id bigint, val ratio);

-- this works

-- insert into my_ratios (id, val) values (1, (22, 7)) returning *;

-- this does not work:

-- insert into my_ratios

-- SELECT

-- round(n::float / d * 100)

-- , (n, d) as ratio -- cannot cast type record to ratio

-- FROM generate_series(21, 23) n

-- , generate_series(6, 8) d

-- returning *;

-- this works tho:

insert into my_ratios

SELECT

round(n::float / d * 100)

, cast(cast((n, d) as text) as ratio)

FROM generate_series(21, 23) n

, generate_series(6, 8) d

returning *;