根据时间戳获取上一个和下一个网址

Question

I have a page that displays all projects ordered by dates. When you click on a project you are brought to a page project-single.php?id=123 where I have a previous and next button. All of the projects have an id (which is in no sequential order aka not auto_incremented), and a date of creation timestamp (in the form of 2012-07-20 00:36:20) in the projects table in the database. I am trying to think of an efficient way to get the id of the project both before and after the id=123 in terms of date for the prev next buttons. But I cannot think of an easier way than creating an array with the id and date_created and comparing dates; which as you can imagine would get quite taxing on the server as this is a page accessed often. Does anyone have a cleaner solution?

Answer 1

You might consider changing your timestamp to a Unix timestamp instead of a string. Unix timestamps are simple integers, which are easy and efficient for a database to compare.

With a comparison operator, an index on the timestamp, and a LIMIT 1, you should have a very fast SQL statement. Here's some example code:

-- For getting the next project.
SELECT * FROM projects WHERE date_created > :current_project_date ORDER BY date_created ASC LIMIT 1;
-- For getting the previous project.
SELECT * FROM projects WHERE date_created < :current_project_date ORDER BY date_created DESC LIMIT 1;

I'm not familiar with MySQL, so these results may need some tweaking, but that's the gist.