CREATE TYPE screen_type AS ENUM ('regular', 'stereo', '3d');
create table halls (
id serial primary key,
name text,
seets_count int,
screen screen_type
);
insert into halls (name, seets_count, screen) values ('Blue', 25, 'regular');
insert into halls (name, seets_count, screen) values ('Gold', 15, '3d');
select * from halls;
ALTER TYPE screen_type ADD VALUE '4d';