MySQL Update Column +1?

Question

I was wondering what would be the easiest way to update a column by +1? I will be updating a post count of a category based on when users submits a new post.

Thanks.

Answer 1

The easiest way is to not store the count, relying on the COUNT aggregate function to reflect the value as it is in the database:

   SELECT c.category_name,           COUNT(p.post_id) AS num_posts      FROM CATEGORY c LEFT JOIN POSTS p ON p.category_id = c.category_id 

You can create a view to house the query mentioned above, so you can query the view just like you would a table...

But if you're set on storing the number, use:

UPDATE CATEGORY    SET count = count + 1  WHERE category_id = ? 

..replacing "?" with the appropriate value.

Answer 2

You can do:

UPDATE categories SET posts = posts + 1 WHERE category_id = 42;