mySQL rank order by sum of values in table - mysql

Question

I have a mySQL database table I'm using to store messages sent out to people. Each message can contain points. I am wondering if there is a query that would sum up all the points per person and order them by rank?
Currently the only way I know how to get the output I'm looking for is to run this:
SELECT SUM(messagePoints) AS totalPoints FROM Messages
then store the result in PHP and order the result by totalPoints. I'm sure there is a way to do this entirely with a query but I don't have a clue where to start. Hoping somebody can give me some advice.
Messages Table example
messageID | personID | dateOfMessage | messagePoints
----------------------------------------------------------------
1 | 10 | 2017-01-05 00:00:00 | 5
2 | 10 | 2017-01-16 00:00:00 | 3
3 | 20 | 2017-01-16 00:00:00 | 4
4 | 10 | 2017-02-01 00:00:00 | 6
5 | 20 | 2017-02-07 00:00:00 | 7
Ideal Result:
personID | totalPoints | rank
--------------------------------
10 | 14 | 1
20 | 11 | 2
If the above output is possible, I'm wondering if it is possible to produce the same output with a date range filter such as only messages from the month of February.
Ideal Result only February messages:
personID | totalPoints | rank
--------------------------------
20 | 7 | 1
10 | 6 | 2
EDIT:
If it's easier, I ultimately need to display in my application the totalPoints and rank for 1 person (to be supplied by PHP) i.e. just results for personID = 10 I need both totalPoints and rank overall and filtered by date. So maybe 4 separate queries.
Ideal Overall Result for personID=10:
totalPoints
-----------
14
and
rank
----
1
Ideal Result for personID=10 Filtered by February:
totalPoints
-----------
6
and
rank
----
2

Answer 1

If you don't need the rank in the result - this is a basic aggregation query:
select m.personID, sum(messagePoints) as totalPoints
from messages m
group by m.personID
order by totalPoints desc
One way to include a row number (rank) to the result is to use a temporary table with an AUTO_INCREMENT column for the rank:
drop temporary table if exists tmp_messages;
create temporary table tmp_messages(
rank int auto_increment primary key,
personID int,
totalPoints int
) as
select null as rank, m.personID, sum(messagePoints) as totalPoints
from messages m
group by m.personID
order by totalPoints desc;
select * from tmp_messages order by rank;
You can ofcourse include fllters in the WHERE clause like:
select m.personID, sum(messagePoints) as totalPoints
from messages m
where m.dateOfMessage >= '2017-02-01'
and m.dateOfMessage < '2017-03-01'
group by m.personID
And you can select a specific user:
select * from tmp_messages where personID = 10
Demo: http://rextester.com/ASWF7717

Answer 2

You can try the below code to get the rank and you can use where clause to filter for dates.
select personID, SUM(messagePoints) AS totalPoints,#curRank := #curRank + 1 AS rank
from Messages, (select #curRank :=0) r
group by personID
order by totalPoints