sql - MySQL reference row in sub query -


i'm trying count messages sent users after uploaded photo.

i'm trying this.

select messages.created_at, count(*) count messages        inner join users on messages.user_id = users.id       inner join photos on photos.user_id = users.id                some_users_messages.created_at > some_users_first_photo.created_at       group yearweek(messages.created_at)

i'm thinking needs subquery? i'm not sure how concept of 1 particular user's messages/photos in mysql. ideas?

thanks!

this count number of messages sent after first photo per user:

select  messages.user_id ,       count(*) count     messages    messages.created_at >         (         select  min(created_at)            photos           photos.user_id = messages.user_id         ) group          messages.user_id

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