How to write a constraint concerning a max number of rows in postgresql?

Question

I think this is a pretty common problem.

I\'ve got a table user(id INT ...) and a table photo(id BIGINT, owner INT). owner is a reference o

Answer 1

A better alternative would be to check the number of rows when you do the insert:

insert into photos(id,owner) 
select 1,2 from dual
where (select count(*) from photos where id=1) < 10