Vjeux

In SQL, this is a common issue to query the previous and next entries of the database. In order to achieve this, we are going to use a table that is sorted by the `id` field. To get the previous, the technique consists in sorting all the fields that are lower that the current one and taking the first one.

SELECT *
FROM `table`
WHERE `id` < $current_id
ORDER BY `id` DESC
LIMIT 1

Let’s take an example with the values [8, 3, 4, 9, 6, 1]. We want to get the previous of 8.

• WHERE `id` < $current_id
  We first take all the values strictly lower than 8
  Result: [3, 4, 1, 6]
• ORDER BY `id` DESC
  We then sort them in descending order
  Result: [6, 4, 3, 1]
• LIMIT 1
  We take the first one
  Result: 6

You can apply the same method for the next entry:

SELECT *
FROM `table`
WHERE `id` > $current_id
ORDER BY `id` ASC
LIMIT 1