按两列排序MySQL

Question

I am implementing a Popular feature into my app where I will select the most popular posts from a database. Problem is I need to get the most popular in terms of most likes and most comments. I just tried:

SELECT * FROM db ORDER BY `likesCount`,`commentsCount` DESC LIMIT $from," . ($to-$from)

But that will show an ascending value in terms of the numberOfLikes. How can I get it so that it measures the numberOfLikes and numberOfComments and selects the most popular one?

Answer 1

You can specify whether you want to sort in ascending or descending order for each search field.

SELECT * FROM `db` ORDER BY `likesCount` DESC, `commentsCount` DESC

With that said, you won't be able to select the most like and most commented ones at the same time. You'll have to come up with a formula to figure that out. For instance, the example below find the maximum value for a given "id" between the number of likes and comments:

SELECT * FROM `db` GROUP BY `id` ORDER BY GREATEST(`likesCount`, `commentsCount`) DESC

Another alternative would be to add them together:

SELECT * FROM `db` ORDER BY `likesCount` + `commentsCount` DESC

Answer 2

Don't you want to order by total number of likes and comments? Does one of these weigh more than the other when it comes to popularity?

You could just do:

SELECT *, (`likesCount` + `commentsCount`) as popularity FROM db ORDER BY popularity DESC ...

As mistercruffles suggested below, you can add in a multiplier to have one factor weigh more than the other. Just change ( likesCount + commentsCount ) with (X* likesCount + Y* commentsCount ) where X is the factor for likes and Y is for comments. For X = 2 and Y = 1, it means that likes are two times more important than comments, but I'm sure you figured that out.

Answer 3

If you want to weight likes more than comments, you can use:

SELECT * FROM `db` ORDER BY (3*`likesCount` + 2*`commentsCount`) DESC

Which will weight likes more than comments in a 3:2 ratio, ie 50% stronger. I'm not sure whether you want this or are would prefer to choose the higher of the two counts to rank by, but want to weight them before determining the higher of the two. If the latter is what you are looking for then this should do the trick:

SELECT * FROM `db` ORDER BY greatest(3*`likesCount`, 2*`commentsCount`) DESC