Okay so lets say I have a basic table
thing
id
user_id
created_at
And some data
id user_id created_at
1 1 2016-09-06
2 1 2016-09-06
3 1 2016-09-06
4 1 2016-09-07
5 1 2016-09-08
6 1 2016-09-08
7 1 2016-09-08
What I want to achive is selecting max two rows per USER per DATE of created_at. I'm only displaying data from one user, but I hope you get the point.
So the results of the select should be
id user_id created_at
1 1 2016-09-06
2 1 2016-09-06
4 1 2016-09-07
5 1 2016-09-08
6 1 2016-09-08
I know I somehow have to use the LIMIT keyword, but I'm not so sure how. I'm also pretty sure I have to use a subquery and group by the date.
I hope you understand the problem and please do ask some questions if there's something difficult to understand.
One way is to use variables:
SELECT id, user_id, created_at
FROM (
SELECT id, user_id, created_at,
#rn := IF(#dt = created_at, #rn + 1,
IF(#dt := created_at, 1, 1)) AS rn
FROM mytable
CROSS JOIN (SELECT #rn := 0, #dt := '1900-01-01') AS var
ORDER BY created_at) AS t
WHERE t.rn <= 2
Demo here
Related
I asked this question yesterday, but I didn't make it clear enough as it seems, so I'm gonna add some information to make everything clear.
Consider the following 2 tables:
0_12_table
ID userID text timestamp
1 1 bla 2020-08-07 10:30:00
2 1 blub 2020-08-06 11:30:00
3 1 abc 2020-08-05 09:20:00
4 1 def 2020-08-04 06:13:00
5 2 ghi 2020-08-02 08:05:00
6 2 abc 2020-08-05 10:20:00
7 3 def 2020-08-04 07:13:00
8 4 ghi 2020-08-02 09:05:00
9 5 jkl 2020-08-07 06:30:00
10 5 mno 2020-08-08 08:32:00
12_24_table:
ID userID text timestamp
1 1 bla 2020-08-07 19:30:00
2 1 blub 2020-08-06 21:30:00
3 1 abc 2020-08-05 19:20:00
4 2 def 2020-08-04 16:13:00
5 2 ghi 2020-08-02 18:05:00
6 2 abc 2020-08-05 20:20:00
7 3 def 2020-08-04 17:13:00
8 4 ghi 2020-08-02 19:05:00
9 5 jkl 2020-08-07 20:13:00
Basically, users can (and are animated to do so) to add one entry in the databse between 00:00 and 12:00 and one between 12:01 and 23:59.
Now I'd like to reward them for adding consecutive entries. Whenever they miss their timeframe, that "counter" is reset to 0 though...
In the above given data, the user with the userID 1 would have a streak of 3 days right now (in my time, its 9 AM right now), whenever its after 12 AM though, and he didn't make another entry, the counter would be set to 0 and the streak is over, because he missed adding an entry for the morning.
The users with the userID's 2,3 and 4 would have no streak at all. The streak is always cancelled, when there is one morning entry or evening entry missing.
The user with the userID 5 would have a streak of 1, which would increased to 2, whenever he made his entry for the timeframe of 12:01 to 23:59.
I hope you understand the logic. The important part is, that it does NOT matter, if he had a streak of 10 2 days ago. Whenever there is an entry missing, the streak is reset to 0. So when there is no entry until 12 AM on one day for the morning table or when there is no entry for the evening until 23:59, then the streak is gone. It always uses today as reference, so its really "consecutive entries until today".
The answer that seems to be as close as I got so far is the following:
select min(dte), max(dte), count(*)
from (select dte, (#rn := #rn + 1) as seqnum
from (select dte
from ((select date(timestamp) as dte, 1 as morning, 0 as evening
from morning
) union all
(select date(timestamp) as dte, 0 as morning, 1 as evening
from evening
)
) me
group by dte
having sum(morning) > 0 and sum(evening) > 0
order by dte
) d cross join
(select #rn := 0) params
) me
group by dte - interval seqnum day
order by count(*) desc
limit 1;
However, I didn't introduce the userID there so far and the biggest problem: It just takes the last streak, no matter if there is a gap until today.. But, as mentioned, it always takes today as reference.
I hope someone can help me here.
Last important information: I'm using MariaDB 10.1.45, so "WITH" or "ROWNUM()" is not available, updating is not possible right now.
Thanks in advance!
This would really be simpler in a more recent version that uses window functions. But you can adapt the variables to get all streaks for users:
select userid, count(*) as length
from (select dte, (#rn := #rn + 1) as seqnum
from (select dte
from ((select userid, date(timestamp) as dte, 1 as morning, 0 as evening
from morning
) union all
(select userid, date(timestamp) as dte, 0 as morning, 1 as evening
from evening
)
) me
group by userid, dte
having sum(morning) > 0 and sum(evening) > 0
order by userid, dte
) d cross join
(select #rn := 0) params
) me
group by userid, dte - interval seqnum day
order by count(*) desc;
It turns out that a "global" sequence works as well as local sequences for this problem, so the variable use is still simple. The changes are to the group by and order by clauses.
You can then use this as a subquery to get the maximum:
select userid, max(seq)
from (select userid, count(*) as seq
from (select dte, (#rn := #rn + 1) as seqnum
from (select dte
from ((select userid, date(timestamp) as dte, 1 as morning, 0 as evening
from morning
) union all
(select userid, date(timestamp) as dte, 0 as morning, 1 as evening
from evening
)
) me
group by userid, dte
having sum(morning) > 0 and sum(evening) > 0
order by userid, dte
) d cross join
(select #rn := 0) params
) me
group by userid, dte - interval seqnum day
) u
group by userid;
Note: Users with no streaks would be filtered out. You can put them back in using a left join in the outer query. However, you would really want a table of all users for this, rather than your two separate tables, so I haven't bothered.
I would like to create the MonthCount column described below. I have the ID and Date fields already created I am just having trouble thinking of a clever way to count the number of dates that have passed. The dates are always the first of the month, but the first month could be any month between Jan and Dec.
ID Date MonthCount
1 1/2016 1
1 2/2016 2
1 3/2016 3
2 5/2015 1
2 6/2015 2
2 7/2015 3
It seems like I remember reading somewhere about joining the table to itself using a > or < operator but I can't completely recall the method.
The best way to handle this in MySQL is to use variables:
select t.*,
(#rn := if(#id = id, #rn + 1,
if(#id := id, 1, 1)
)
) as rn
from t cross join
(select #rn := 0, #id := -1) params
order by id, date;
It looks like you're looking for:
select a.id, a.date, b.mindate
from table as a
inner join (
select id, min(date) as mindate
from table
group by id
) as b on (a.id=b.id)
this will give you
ID Date mindate
1 1/1/2016 1/1/2016
1 1/2/2016 1/1/2016
1 1/3/2016 1/1/2016
2 1/5/2015 1/5/2015
2 1/6/2015 1/5/2015
2 1/7/2015 1/5/2015
now homework for you is to figure out how to calculate difference between two dates
I am trying to group by two columns they are dependent each other
Example:
id date status
1 2016-03-04 0
2 2016-03-05 0
3 2016-03-04 1
4 2016-03-04 0
5 2016-03-05 1
Result:
id date status
1 2016-03-04 0
2 2016-03-04 0
3 2016-03-04 1
4 2016-03-05 0
5 2016-03-05 1
I tried order by datewise and stautswise (ex show 0 status record first after that another date)
pls help me
I think you are just looking for a proper order by:
select t.*
from t
order by date, status;
If you want to calculate the id, then variables will help:
select (#rn := #rn + 1) as id, t.*
from t cross join
(select #rn := 0) params
order by date, status;
As i am getting your requirement it work ......
select min(e1.id),min(e1.date),e1.status
from example
inner join result r1 on e1.id =r1.id
group by e1.status
if its not your requirement then please let me know i ll update as per your
requirement.
Use only Order By Clause with both column
SELECT *
FROM tblname
Order By datecol,status
http://sqlfiddle.com/#!9/f8b55/1
I have a table that keeps track of the scores of people playing my game
userID | game_level | date_of_attempt | score
1 1 2014-02-07 19:29:00 2
1 2 2014-02-08 19:00:00 0
2 1 2014-03-03 11:11:04 4
... ... ... ...
I am trying to write a query that, for a given user, will tell me their cumulative score for each game_level as well as they average of the last 20 scores they have obtained on a particular game_level (by sorting on date_of_attempt)
For example:
userID | game_level | sum of scores on game level | average of last 20 level scores
1 1 26 4.5
1 2 152 13
Is it possible to do such a thing in a single query? I often need to perform the query for multiple game_levels, and I use a long subquery to work out which levels are needed which makes me think a single query would be better
MySQL does not support analytic functions, so obtaining the average is trickier than it would be in some other RDBMS. Here I use user-defined variables to obtain the groupwise rank and then test on the result to average only over the 20 most recent records:
SELECT userID, game_level, SUM(score), x.avg
FROM my_table JOIN (
SELECT AVG(CASE WHEN (#rank := (CASE
WHEN t.userID = #userID
AND t.game_level = #gamelevel
THEN #rank + 1
ELSE 0
END) < 20 THEN score END) AS avg,
#userID := userID AS userID,
#game_level := game_level AS game_level
FROM my_table,
(SELECT #rank := #userID := #game_level := NULL) init
ORDER BY userID, game_level, date_of_attempt DESC
) x USING (userID, game_level)
GROUP BY userID, game_level
See How to select the first/least/max row per group in SQL for further information.
I have data in a table like this:
fgid qty ntid
1 100 10
2 90 10
6 200 11
1 80 11
1 120 12
6 100 12
6 30 13
And i make query :
SELECT fgid, SUM(qty) AS total_qty, COUNT(ntid) AS nt_count FROM sofg
GROUP BY fgid
AND the result is :
fgid total_qty nt_count
1 300 3
2 90 1
6 330 3
Then i want to make the result like this :
no fgid total_qty nt_count
1 1 300 3
2 2 90 1
3 6 330 3
How to do that with a query? where 'no' is (like) autoincrement number.
Try this query.
SELECT
#rownum := #rownum + 1 rownum,
t.*
FROM (SELECT #rownum:=0) r,
(
SELECT fgid, SUM(qty) AS total_qty, COUNT(ntid) AS nt_count FROM sofg GROUP BY fgid
) t;
Basically the same as Dhinakaran's answer, but there's no need to put the whole main query into a subquery. There's no difference to his answer appart from maybe being more pleasing to the eye, but please accept Dhinakaran's answer, as he was faster.
SELECT
#rownum:=#rownum + 1 as rownumber,
fgid,
SUM(qty) AS total_qty,
COUNT(ntid) AS nt_count
FROM sofg
, (select #rownum:=0) v
GROUP BY fgid