My first query
SELECT
id,
year_,
month_
FROM
(SELECT
tp.id,
YEAR(FROM_UNIXTIME(tp.visited_date)) as year_,
MONTH(FROM_UNIXTIME(tp.visited_date)) as month_,
#rn := IF(#prev = CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)),MONTH(FROM_UNIXTIME(tp.visited_date))), #rn + 1, 1) AS rn,
#prev := CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)),MONTH(FROM_UNIXTIME(tp.visited_date)))
FROM
tr_place tp
JOIN
(SELECT #prev := NULL, #rn := 0) AS vars
ORDER BY
YEAR(FROM_UNIXTIME(tp.visited_date)) DESC,
MONTH(FROM_UNIXTIME(tp.visited_date)) DESC) AS T1
WHERE
rn < 3;
Will returns the data set This is the result which I got from the query
The subquery in it
SELECT
tp.id,
YEAR(FROM_UNIXTIME(tp.visited_date)) as year_,
MONTH(FROM_UNIXTIME(tp.visited_date)) as month_,
#rn := IF(#prev = CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)),MONTH(FROM_UNIXTIME(tp.visited_date))), #rn + 1, 1) AS rn,
#prev := CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)),MONTH(FROM_UNIXTIME(tp.visited_date)))
FROM
tr_place tp
JOIN
(SELECT #prev := NULL, #rn := 0) AS vars
ORDER BY
YEAR(FROM_UNIXTIME(tp.visited_date)) DESC,
MONTH(FROM_UNIXTIME(tp.visited_date)) DESC;
Returns data The sub query will returns this data
I need the subquery's greatest rn as a column in the first query.
How can I achieve that?
You may be having a problem with variable assignment. You should not be referencing variables in multiple expressions in the select. So, the correct way to write the first query is:
SELECT id, year_, month_
FROM (SELECT tp.id,
YEAR(FROM_UNIXTIME(tp.visited_date)) as year_,
MONTH(FROM_UNIXTIME(tp.visited_date)) as month_,
(#rn := IF (#prev = CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)), MONTH(FROM_UNIXTIME(tp.visited_date))), #rn,
if(#prev := CONCAT(YEAR(FROM_UNIXTIME(tp.visited_date)), MONTH(FROM_UNIXTIME(tp.visited_date))), 1, 1
)
) as rn
FROM tr_place tp JOIN
(SELECT #prev := NULL, #rn := 0) AS vars
ORDER BY YEAR(FROM_UNIXTIME(tp.visited_date)) DESC,
MONTH(FROM_UNIXTIME(tp.visited_date)) DESC
) t1
WHERE rn < 3;
Note the variable assignments are all in a single expression.
This may fix your issue.
Related
Need to find median value of time difference between sent date and click date (in seconds) for each type of emails. I found solution just for all data:
SET #rowindex := -1;
SELECT g.type, g.time_diff
FROM
(SELECT #rowindex:=#rowindex + 1 AS rowindex,
TIMESTAMPDIFF(SECOND, emails_sent.date_sent, emails_clicks.date_click) AS time_diff,
emails_sent.id_type AS type
FROM emails_sent inner join emails_clicks on emails_sent.id = emails_clicks.id_email
ORDER BY time_diff) AS g
WHERE g.rowindex IN (FLOOR(#rowindex / 2) , CEIL(#rowindex / 2));
Is it possible to add group by id_type statement?
Thanks!
First, you need to enumerate the rows for each type. Using variables, this code looks like:
select sc.*,
(#rn := if(#t = id_type, #rn + 1,
if(#t := id_type, 1, 1)
)
) as seqnum
from (select timestampdiff(second, s.date_sent, c.date_click) as time_diff,
s.id_type,
from emails_sent s inner join
emails_clicks c
on s.id = c.id_email
order by time_diff
) sc cross join
(select #t := -1, #rn := 0) as params;
Then, you need to bring in the total number for each type and do the calculation for the median:
select sc.id_type, avg(time_diff)
from (select sc.*,
(#rn := if(#t = id_type, #rn + 1,
if(#t := id_type, 1, 1)
)
) as seqnum
from (select timestampdiff(second, s.date_sent, c.date_click) as time_diff,
s.id_type,
from emails_sent s inner join
emails_clicks c
on s.id = c.id_email
order by time_diff
) sc cross join
(select #t := -1, #rn := 0) as params
) sc join
(select id_type, count(*) as cnt
from emails_sent s inner join
emails_clicks c
on s.id = c.id_email
group by id_type
) n
where 2 * seqnum in (n.cnt, n.cnt, n.cnt + 1, n.cnt + 2)
group by sc.id_type;
I have mysql table called ware_stock_transaction and it has order_no, order_type, created_date, item_no.
I want to get the last 10 record from each item, like this:
item A (10 records)
item B (10 records)
item C (10 records)
In MySQL, you can use variables:
select wst.*
from (select wst.*,
(#rn := if(#i = item_no, #rn + 1,
if(#i := item_no, 1, 1)
)
) as rn
from ware_stock_transaction wst cross join
(select #rn := 0, #i := '') params
order by item_no, created_date desc
) wst
where rn <= 10;
How delete duplicate data except two row?
id 4 must deleted, because 'mangga' already have 3 row
This is a bit painful in MySQL. The following identifies the rows to be deleted:
select t.*
from (select t.*,
(#rn := if(#n = nama, #rn + 1,
if(#n := nama, 1, 1)
)
) as rn
from t cross join
(select #n := '', #rn := 0) params
order by nama, id
) t
where rn > 2;
You can then do the delete using a join:
delete t
from t join
(select t.*,
(#rn := if(#n = nama, #rn + 1,
if(#n := nama, 1, 1)
)
) as rn
from t cross join
(select #n := '', #rn := 0) params
order by nama, id
) tt
on t.id = tt.id
where tt.rn > 2;
http://sqlfiddle.com/#!9/083f5d/1
It's returning 6th rank instead of 1st rank in above SQL query. What changes I need to do in SQL query so it provides 1st rank because I have used WHERE condition to check mpkid and roundpkid (WHERE mpkid=37 AND roundpkid=3).
Here is the query:
SELECT mpkid, totalvote, rank
FROM (
SELECT mpkid, roundpkid, totalvote,
#n := IF(#g = totalvote, #n, #n + 1) rank,
#g := totalvote
FROM tr_msearch_vote_summary,
(SELECT #n := 0) i
ORDER BY totalvote DESC
) q
WHERE mpkid=37 AND roundpkid=3
What I want:
Please see sqlfiddle first. There is only one record for round #3, and it is 37 so I want that it should display rank #1 for mpkid #37 and round #3 but it is giving rank #6.
You are applying the WHERE condition after the ranking is already complete. I'm guessing you want to do the ranking after the WHERE is applied:
SELECT t.mpkid, t.roundpkid,
#n := IF(#g = t.totalvote, #n, #n + 1) rank,
#g := t.totalvote totalvote
FROM tr_msearch_vote_summary t, (SELECT #n := 0) i
WHERE t.mpkid=37 AND t.roundpkid=3
ORDER BY t.totalvote DESC
You should also initialise #g to make sure it isn't preset in another query:
SELECT t.mpkid, t.roundpkid,
#n := IF(#g = t.totalvote, #n, #n + 1) rank,
#g := t.totalvote totalvote
FROM tr_msearch_vote_summary t, (SELECT #n := 0, #g := NULL) i
WHERE t.mpkid=37 AND t.roundpkid=3
ORDER BY t.totalvote DESC
UPDATE
If you want the ranking grouped by round and then to simply SELECT by mpkid, this is a more powerful query:
SELECT mpkid,
roundpkid,
totalvote,
rank
FROM (
SELECT t.mpkid,
#n := CASE
WHEN #r = t.roundpkid AND #g = t.totalvote THEN #n
WHEN #r = t.roundpkid THEN #n + 1
ELSE 1
END rank,
#r := t.roundpkid roundpkid,
#g := t.totalvote totalvote
FROM tr_msearch_vote_summary t, (SELECT #n := 0, #g := NULL, #r := NULL) i
ORDER BY t.roundpkid, t.totalvote DESC
) r
WHERE mpkid = 37;
Note that you do not need to supply the roundpkid. See updated fiddle
Please try this query,
SELECT mpkid, totalvote, rank
FROM (
SELECT mpkid, roundpkid, totalvote,
#n := IF(#g = totalvote, #n, #n + 1) rank,
#g := totalvote
FROM tr_msearch_vote_summary,
(SELECT #n := 0) i
WHERE roundpkid=3
ORDER BY totalvote DESC
) q
WHERE mpkid=37
And here is your updated sqlfiddle. http://sqlfiddle.com/#!9/083f5d/9
I've been playing with this SQL code:
SELECT
id,
#prev := #curr as prev,
#curr := measure as curr,
#rank := IF(#prev > #curr, #rank+#ties, #rank) AS rank,
#ties := IF(#prev = #curr, #ties+1, 1) AS ties,
(1-#rank/#total) as percentrank
FROM
mytable,
(SELECT
#curr := null,
#prev := null,
#rank := 0,
#ties := 1,
#total := count(*) from mytable where measure is not null
) b
WHERE
measure is not null
ORDER BY
measure DESC
I'd like to write the calculated 'percentrank' back to each corresponding row of mytable in a column named "percentile," but I can't recall how to work in my update statement.
I appreciate the help.
Credit to http://code.openark.org/blog/mysql/sql-ranking-without-self-join for the SQL.
To update from a subquery, give the subquery an alias so that it's a derived table. Then use this syntax:
update YourTable
set SomeField = DerivedTable.something
, etc
from YourTable join
(subquery goes here) DerivedTable on YourTable.Whatever = DerivedTable.Whatever
etc