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create table a ( string_id integer, language CHAR(2), value varchar ); insert into a values (1, 'en', 'Yes'), (1, 'ru', 'Да'); create or replace function check_string_id() returns trigger as $BODY$ begin if not exists (select 1 FROM a WHERE string_id = new.string_id ) then raise exception 'check string_id failed'; return null; else return new; end if; end; $BODY$ LANGUAGE plpgsql; create table b ( id UUID, string_id int ); CREATE TRIGGER check_insert BEFORE INSERT ON b FOR EACH ROW EXECUTE PROCEDURE check_string_id(); insert into b values (null, 1); insert into b values (null, 2); select * from b;