# $602. 好友申请 II ：谁有最多的好友
# https://leetcode-cn.com/problems/friend-requests-ii-who-has-the-most-friends/

# SQL架构
Create table If Not Exists RequestAccepted (requester_id int not null, accepter_id int null, accept_date date null);
Truncate table RequestAccepted;
insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '2', '2016/06/03');
insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('1', '3', '2016/06/08');
insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('2', '3', '2016/06/08');
insert into RequestAccepted (requester_id, accepter_id, accept_date) values ('3', '4', '2016/06/09');

# Write your MySQL query statement below
select
    id,
    count(*) as num
from
    (
        select
            requester_id as id
        from
            RequestAccepted
        union
        all
        select
            accepter_id
        from
            RequestAccepted
    ) tmp
group by
    id
order by
    count(*) desc
limit
    1;

# clean-up
drop table RequestAccepted;