ORDER BY the IN value list

🎉 How to Sort the Resulting Rows Based on the IN Value List in PostgreSQL 8.3 🎉

So, you're here because you've run into a tricky situation while working with a SQL query in PostgreSQL 8.3. You've used the IN construct in the WHERE clause to fetch a bunch of comments, but you're facing an issue with the order of the resulting rows. But worry not, because we've got your back! In this guide, we'll show you how to sort the rows based on the IN value list. Let's dive right in! 💪

The Problem: Unsorted Resulting Rows

In your case, you have a simple SQL query that looks like this:

SELECT * FROM comments WHERE (comments.id IN (1, 3, 2, 4));

While this query retrieves the comments you need, the order of the resulting rows is arbitrary. You were expecting the rows to be sorted based on the values in the IN construct, which are (1, 3, 2, 4).

The Solution: Using PostgreSQL ARRAY and unnest()

To sort the resulting rows based on the IN value list, we'll make use of PostgreSQL's ARRAY and unnest() functions. Here's how you can achieve it:

SELECT * FROM comments 
WHERE comments.id IN (SELECT unnest(ARRAY[1, 3, 2, 4]) ORDER BY unnest_position);

Let's break this down step by step:

1. First, we create an array of the values in the IN construct using the ARRAY function. In this case, it's [1, 3, 2, 4].

2. Next, we use the unnest() function to convert the array into a set of rows. By default, unnest() adds a new column called unnest which contains the original array values.

3. To preserve the original order of the items in the array, we add the ORDER BY unnest_position clause. This sorts the resulting rows according to the position of the items in the array.

And voila! 🎊 You'll now receive the rows in the desired order: (1, 3, 2, 4).

Your Turn: Give It a Try!

Now that you know the solution, it's time to put it into action and see the magic happen! Update your SQL query with the provided solution, run it, and experience the joy of seeing the resulting rows sorted as expected.

If you encounter any difficulties or have any further questions, feel free to drop a comment below. We're always here to help! 😊

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Happy coding! 💻✨