Question

My database has news articles and blog posts. The primary key for both is an ItemID that is unique across both tables.

The articles are in a table that has the following fields

• item_id
• title
• body
• date_posted

The blogposts table has the following fields

• item_id
• title
• body
• date_posted

both tables have extra fields unique to them.

I have a third table that holds meta information about articles and posts.

The items table has the following fields

• item_id
• source_id
• …

every blogpost and article has a record in the items table and a record in its respective table.

What I am trying to do is build a query that will count the number of items posted per day. I can do it for one table using a count grouped by date_posted but how to combine articles and posts count in one query?

Answer 1

Similar to Dems, but slightly simpler:

select date_posted, count(*)
from (select date_posted from article union all
      select date_posted from blogposts) v
group by date_posted