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

You cannot write such a constraint in a table declaration.

There are some workarounds:

• Create a trigger that would check the number of photos for each user
• Create a photo_order column that would keep the order of photos, make (user_id, photo_order) UNIQUE, and add CHECK(photo_order BETWEEN 1 AND 10)