I have 3 types of content: blogs, press releases, and reminders. All of them have a body and entered by fields. The blogs and press releases have a title field, which the reminder lacks, and the reminders has an hour field, which blogs and press releases lack. This is what it looks like in tabular format so it's easy for you to see...

                   blog       press release      reminder
---------------------------------------------------
entered by field   yes        yes                yes
body field         yes        yes                yes
title field        yes        yes                --
time field         --         --                 yes

I'm creating a main table called content that links to the specialized tables blogs press releases reminders. I thought of 2 structures

First structure... This is how the content management system I use does it, but I don't want to follow in their steps blindly because my needs are not the same. Put ALL shared fields in the main content table. So the content table will not only have type and type id to link to the specialized tables, the content table will also have the common fields like body and entered by. The other 3 tables only have their unique fields.

content table    B=blogs table   PR=press releases table     R=reminders table
------------------------------------------------------------------------------
id               id              id                          id
type=B/PR/R      title           title                       hour
type id
body
entered by

Second structure. content table only has the type and type id necessary to link to the other 3 tables, This means that the common fields get repeated in the 3 tables.

content table    B=blogs table   PR=press releases table     R=reminders table
------------------------------------------------------------------------------
id               id              id                          id
type=B/PR/R      entered by      entered by                  entered by 
type id          body            body                        body
                 title           title                       hour

Which should I go with? I thought the first structure is better because I can search all content whether it's a blog or press release or reminder for a specific word. I still have to look in the other tables if I want to search the title which is available only to blogs and press releases, but...

So which structure is better, and why you think so? I'm also open to other ideas or improvements that are different from these 2.

Originally asked by: silow on Stack Overflow