从具有计数和基于计数条件的数据库中选择？

Question

I have a table with data relating to a user, and two important columns:

refer_count , which is updated when a new entry is made in the table with the referred_by column set to that users user_id , and referred_by which is the user_id of the of the user that referred them.

I want to select the users from the table that have the highest number of referrals after a certain date.

For example:

If there are 3 users, one of which referred the other 2 (lets say users 2 and 3 ), however user 2 was referred on the 2/12/14, whereas user 3 was referred on the 3/1/15.

If the cutoff is 1/12/14, then user 1 is returned with refer_count set to 2, but if the cutoff is after 2/12/14, then user 1 is returned with refer_count set to 1.

I've been thinking of how to do this, but I can't think of a way that would work. Is there a way?

This is via MySQL.

EDIT: I think I may need to provide for information.

The date registered ( register_date ) is used as the refer date. I need the refer_count to be updated with the number of users referred after the cutoff, however I need to get the actual user. This is for a 'top referrers' table. I can't figure out why I'm having so much trouble thinking of a way to do this.

Answer 1

SELECT user_id FROM usertable WHERE (referal_date BETWEEN '2014-12-2' AND CURDATE())ORDER BY refer_count DESC;

That's the rough idea. You should look into normalizing your tables if you're keeping that all in the same table, though. It'd be better to keep referals in a seperate table.

Answer 2

Get the row with the maximum in refer_count with a Date condition for your referal_date such that it's after the certainDate :

SELECT user_id FROM table WHERE refer_count = (SELECT MAX(refer_count) FROM table) AND referal_date>certainDate;

Note that WHERE is before SELECT so it will not get the highest count first, but will filter with the date condition then get the highest count.

Edit: Updated query based on edited question.