Create View with rank column in limited amount of data - mysql

Question

So I have an MySQL table structured like this:
CREATE TABLE `spenttime` {
`id` int(11) NOT NULL AUTO_INCREMENT,
`userid` int(11) NOT NULL,
`serverid` int(11) NOT NULL,
`time` int(11) NOT NULL,
`day` int(11) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `dbid_sid_day` (`userid`,`serverid`,`day`)
}
Where I'm storing time spent on my game servers every day for each registered player. time is the amount of time spent, in seconds, day is an unix timestamp of each day (beginning of the day). I want to create an View on my database that will show for each user time spent on server every week, but with an column displaying rank of that time, independent for each server on each week. For example data (for clarify i will use date format Y-M-D instead of unix timestamp for day column on this example):
INSERT INTO `spenttime` (`userid`, `serverid`, `time`, `day`) VALUES
(1, 1, 200, '2013-04-01'),
(1, 1, 150, '2013-04-02'),
(2, 1, 100, '2013-04-02'),
(3, 1, 500, '2013-04-04'),
(2, 2, 400, '2013-04-04'),
(1, 1, 300, '2013-04-08'),
(3, 1, 200, '2013-04-08');
For that data in viev named spenttime_week should appear:
+--------+----------+--------+------------+------+
| userid | serverid | time | yearweek | rank |
+--------+----------+--------+------------+------+
| 1 | 1 | 350 | '2013-W14' | 2 |
| 2 | 1 | 100 | '2013-W14' | 3 |
| 3 | 1 | 500 | '2013-W14' | 1 |
| 2 | 2 | 400 | '2013-W14' | 1 |
| 1 | 1 | 300 | '2013-W15' | 1 |
| 3 | 1 | 200 | '2013-W15' | 2 |
+--------+----------+--------+------------+------+
I know how to generate view wihout rank, i have only troubles with rank column...
How can I make that happen?
//edit
Additionaly, this column MUST appear in viev, I cannot generate It in select from that view, because app where I will use it don't allow that...

Answer 1

First you need to create a first VIEW that sums the spent time for every user on the same week:
CREATE VIEW total_spent_time AS
SELECT userid,
serverid,
sum(time) AS total_time,
yearweek(day, 3) as week
FROM spenttime
GROUP BY userid, serverid, week;
then you can create your view as this:
CREATE VIEW spenttime_week AS
SELECT
s1.userid,
s1.serverid,
s1.total_time,
s1.week,
count(s2.total_time)+1 AS rank
FROM
total_spent_time s1 LEFT JOIN total_spent_time s2
ON s1.serverid=s2.serverid
AND s1.userid!=s2.userid
AND s1.week = s2.week
AND s1.total_time<=s2.total_time
GROUP BY
s1.userid,
s1.serverid,
s1.total_time,
s1.week
ORDER BY
s1.week, s1.serverid, s1.userid
Please see a fiddle here.

Answer 2

Lots of ways you could get the yearweek column, a quick lazy solution to that for clarity (because I doubt you're struggling with that). But here's how you can get the rank.
Use a self join to get dataset including rows with higher time value than current row, then count the rows with higher value:
This is much easier in MSSQL, which is where I live 99% of the time, and where you can just use the RANK() function. I hadn't realised until today there wasn't an equivalent in mysql. Fun to work out how to get the same result without MS's helping hand.
Prep stuff for context:
CREATE TABLE spenttime (userid int, serverid int, [time] int, [day] DATETIME)
CREATE TABLE weeklookup (weekname VARCHAR(10), weekstart DATETIME, weekend DATETIME)
INSERT INTO spenttime (userid, serverid, [time], [day]) VALUES
(1, 1, 200, '2013-apr-01'),
(1, 1, 150, '2013-apr-02'),
(2, 1, 100, '2013-apr-02'),
(3, 1, 500, '2013-apr-04'),
(2, 2, 400, '2013-apr-04'),
(1, 1, 300, '2013-apr-08'),
(3, 1, 200, '2013-apr-08');
INSERT INTO weeklookup(weekname, weekstart, weekend) VALUES
('2013-w14', '01/apr/2013', '08/apr/2013'),
('2013-w15', '08/apr/2013', '15/apr/2013')
GO
CREATE VIEW weekgroup AS
SELECT a.userid ,
a.serverid ,
a.[time] ,
w1.weekname
FROM spenttime a
INNER JOIN weeklookup w1 ON [day] >= w1.weekstart
AND [day] < w1.weekend
GO
Select statement for the view:
SELECT wv1.userid ,
wv1.serverid ,
wv1.[time] ,
wv1.weekname AS yearweek ,
COUNT(wv2.[time]) + 1 AS rank
FROM weekgroup wv1
LEFT JOIN weekgroup wv2 ON wv1.[time] < wv2.[time]
AND wv1.weekname = wv2.weekname
AND wv1.serverid = wv2.serverid
GROUP BY wv1.userid ,
wv1.serverid ,
wv1.[time] ,
wv1.weekname
ORDER BY wv1.weekname ,
wv1.[time] DESC

Answer 3

If you want to store the rank, you would use an insert trigger. The insert trigger would calculate the rank, as something like:
select count(*)
from spenttime_week w
where w.yearweek = new.yearweek and time >= new.time
However, I would not recommend this, because you then have to create an update trigger as well, and modify rank values that are already inserted.
Instead, access the table using SQL like:
select w.*,
(select count(*) from spenttime_week w2 where w2.yearweek = w.yearweek and w2.time >= w.time
) as rank
from spenttime_week w
This SQL may vary, depending on how you want to handle ties in the data. For performance reasons, you should have an index on at least yearweek, and probably on yearweek, time.