What I am trying to do it with below code, getting all keywords with their positions via LEFT JOIN, it works fine but it shows the first position of each keyword, but I want to show the last position that recorded (by date).
SELECT keyword.id, keyword.title, keyword.date, rank.position FROM keyword
LEFT JOIN rank
ON rank.wordid = keyword.id
GROUP BY keyword.id
ORDER BY keyword.date DESC
How can I do this? Should I use subquery or what? Is there any way to do this without a subquery?
SAMPLE DATA
What I want:
Get 17 instead of 13, I mean last record of position.
Do not use group by for this! You want to filter, so use a where clause. In this case, using a correlated subquery works well:
SELECT k.id, k.title, k.date, r.position
FROM keyword k LEFT JOIN
rank r
ON r.wordid = k.id AND
r.date = (SELECT MAX(r2.date)
FROM rank r2
WHERE r2.wordid = k.id
)
ORDER BY k.date DESC
You can use below query
SELECT keyword.id, keyword.title, keyword.date, rankNew.position FROM keyword LEFT JOIN (
SELECT rank.wordid, rank.position FROM rank ORDER BY rank.id DESC LIMIT 0, 1) AS rankNew ON (rankNew.wordid = keyword.id);
You can get more reference from Retrieving the last record in each group - MySQL
Related
I have an SQL Query (MySQL) which uses a combination of LEFT JOIN, GROUP BUY, ORDER BY, and LIMIT. When I remove LEFT JOIN and GROUP BY it works fine. What is the correct way to add in my additional LEFT JOIN and GROUP logic to make this work?
SELECT tbl_headlines.*, count(tbl_weekly_builds.id) as related_count
FROM tbl_headlines
LEFT JOIN tbl_weekly_builds ON tbl_headlines.id = tbl_weekly_builds.headline
GROUP BY tbl_headlines.id
WHERE tbl_headlines.deleted is null
ORDER BY LOWER(tbl_headlines.label) asc
LIMIT 0, 100;
Your syntax is incorrect - where clause will be before group by
SELECT tbl_headlines.id, count(tbl_weekly_builds.id) as related_count
FROM tbl_headlines
LEFT JOIN tbl_weekly_builds ON tbl_headlines.id = tbl_weekly_builds.headline
WHERE tbl_headlines.deleted is null
GROUP BY tbl_headlines.id
ORDER BY LOWER(tbl_headlines.label) asc
LIMIT 0, 100;
I have a problem. I want to use subquery tm in LEFT JOIN .. ON
SELECT t.*,
(SELECT `uid` FROM `truck_transport` tm WHERE tm.from = t.station ORDER BY RAND() LIMIT 1) as tm
FROM `truck_trailer` t
LEFT JOIN `truck_transport` tm2 ON (tm2.uid = tm) ...
If I use subquery in FROM result of rand is always the same.
Sorry for my language :/
try this
SELECT t.*, tm.uid
FROM `truck_trailer` t
LEFT JOIN (SELECT `uid` FROM `truck_transport` ORDER BY RAND() LIMIT 1) as tm
ON (tm.uid = t.station)
mynawaz has written a correct query.
Your subquery will always return only one result because of limit 1. If you want only one result to come then use JOIN instead of LEFT JOIN. because left join table always returns matching rows and non matching with NULL of right side table.
I have SQL query with LEFT JOIN:
SELECT COUNT(stn.stocksId) AS count_stocks
FROM MedicalFacilities AS a
LEFT JOIN stocks stn ON
(stn.stocksIdMF = ( SELECT b.MedicalFacilitiesIdUser
FROM medicalfacilities AS b
WHERE b.MedicalFacilitiesIdUser = a.MedicalFacilitiesIdUser
ORDER BY stn.stocksId DESC LIMIT 1)
AND stn.stocksEndDate >= UNIX_TIMESTAMP() AND stn.stocksStartDate <= UNIX_TIMESTAMP())
These query I want to select one row from table stocks by conditions and with field equal value a.MedicalFacilitiesIdUser.
I get always count_stocks = 0 in result. But I need to get 1
The count(...) aggregate doesn't count null, so its argument matters:
COUNT(stn.stocksId)
Since stn is your right hand table, this will not count anything if the left join misses. You could use:
COUNT(*)
which counts every row, even if all its columns are null. Or a column from the left hand table (a) that is never null:
COUNT(a.ID)
Your subquery in the on looks very strange to me:
on stn.stocksIdMF = ( SELECT b.MedicalFacilitiesIdUser
FROM medicalfacilities AS b
WHERE b.MedicalFacilitiesIdUser = a.MedicalFacilitiesIdUser
ORDER BY stn.stocksId DESC LIMIT 1)
This is comparing MedicalFacilitiesIdUser to stocksIdMF. Admittedly, you have no sample data or data layouts, but the naming of the columns suggests that these are not the same thing. Perhaps you intend:
on stn.stocksIdMF = ( SELECT b.stocksId
-----------------------------^
FROM medicalfacilities AS b
WHERE b.MedicalFacilitiesIdUser = a.MedicalFacilitiesIdUser
ORDER BY b.stocksId DESC
LIMIT 1)
Also, ordering by stn.stocksid wouldn't do anything useful, because that would be coming from outside the subquery.
Your subquery seems redundant and main query is hard to read as much of the join statements could be placed in where clause. Additionally, original query might have a performance issue.
Recall WHERE is an implicit join and JOIN is an explicit join. Query optimizers
make no distinction between the two if they use same expressions but readability and maintainability is another thing to acknowledge.
Consider the revised version (notice I added a GROUP BY):
SELECT COUNT(stn.stocksId) AS count_stocks
FROM MedicalFacilities AS a
LEFT JOIN stocks stn ON stn.stocksIdMF = a.MedicalFacilitiesIdUser
WHERE stn.stocksEndDate >= UNIX_TIMESTAMP()
AND stn.stocksStartDate <= UNIX_TIMESTAMP()
GROUP BY stn.stocksId
ORDER BY stn.stocksId DESC
LIMIT 1
I have written SQL query with a INNER JOIN and Sub-query:
SELECT c.*,
ar.ArticleName,
ar.idArticle,
du.DetailToUsersName,
du.DetailToUsersPhoto,
COUNT(c.idCommentToArticle) AS CNT,
CASE WHEN d.Count IS NULL THEN 0 ELSE d.Count END AS CountLikes
from (select *
from commenttoarticle g
inner join (select distinct(s.idCommentToArticle)
from commenttoarticle s
order by s.CommentToArticlePID limit 3) as gh) as c
LEFT JOIN article ar ON c.CommentToArticleIdArticle = ar.idArticle
LEFT JOIN detailtousers du ON du.idDetailToUsers = c.CommentToArticleIdUser
LEFT JOIN `likes` d ON (d.IdNote = c.idCommentToArticle AND d.LikeType = 6)
WHERE c.CommentToArticleIdArticle = 11
GROUP BY c.idCommentToArticle
ORDER BY c.idCommentToArticle DESC
So, I get error:
Duplicate column name 'idCommentToArticle'
I can not find where the duplication is?
you can specify in the alias table query c
select g.* from commenttoarticle g
instead of
select * from commenttoarticle g
Also you should specify Join condition to limit the rows to 3 as per your intention, with out the ON clause it will be like a cross join.
select g.* from commenttoarticle g
inner join (select distinct(s.idCommentToArticle) from commenttoarticle s order by s.CommentToArticlePID limit 3) as gh
on g.idcommenttoarticle = gh.idcommenttoarticle
As #RADAR has suggested, your inner query joins don't seem to be complete. And I see from comments that once you place the JOIN condition in, then you lose all data. I think this is because neither part of the subqueries were doing what they were supposed to do.
Here is my attempt at a total solution (note, without dataset and table definition I can't show it working). OK, so you have asked the question again over here and provided a SQL-Fiddle, I have updated with a working version, but minus the additional JOIN tables, since they are not defined.
SELECT c.*,
ar.ArticleName,
ar.idArticle,
du.DetailToUsersName,
du.DetailToUsersPhoto,
COUNT(c.idCommentToArticle) AS CNT,
CASE WHEN d.Count IS NULL THEN 0 ELSE d.Count END AS CountLikes
FROM commenttoarticle c -- one layer of subquery not required.
INNER JOIN (select s.idCommentToArticle, s.CommentToArticlePID -- added both the id and the parent id
FROM commenttoarticle s
WHERE s.CommentToArticleIdArticle = 11 -- moved to inner query, instead of outer query
ORDER BY s.idCommentToArticle DESC limit 3) as gh
ON c.idcommenttoarticle = gh.idcommenttoarticle -- add join condition
OR c.idcommenttoarticle = gh.CommentToArticlePID -- which matches id and parent id
LEFT JOIN article ar ON c.CommentToArticleIdArticle = ar.idArticle
LEFT JOIN detailtousers du ON du.idDetailToUsers = c.CommentToArticleIdUser
LEFT JOIN `likes` d ON (d.IdNote = c.idCommentToArticle AND d.LikeType = 6)
GROUP BY c.idCommentToArticle
ORDER BY c.idCommentToArticle DESC
But let me explain a little further, the following code from your original query was selecting the top 3 idCommentToArticlePID,
(select *
from commenttoarticle g
inner join (select distinct(s.idCommentToArticle)
from commenttoarticle s
order by s.CommentToArticlePID limit 3) as gh)
but then because there was no ON specified the 3 records were then joined to every single record from the g reference. This resulted in the full dataset being returned.
And then you you specified WHERE c.CommentToArticleIdArticle = 11 this filtered the result set back down again to something that looked correct.
When you then added the ON (as per #RADAR's suggestion) the inner query did not contain any values that matched the WHERE c.CommentToArticleIdArticle = 11 filter and thus you lost all your results. If you move this filter into the inner query as shown above, then these will work together and not conflict.
Within the JOIN condition, you indicate that you want both the matching articles and their parents, so I added both to the return of the inner query, and checked for either in the join condition.
Also I think the whole g table reference is redundant and can be removed. You should be able to access this table directly as c.
I also have some concerns about the GROUP BY and COUNT (c.idCommentToArticle) - there seem a little strange, but I have no supporting context (ie data examples), so they may be correct. If you still have issues, I would comment the GROUP BY and COUNT statements out, and test to see what data you are getting, before adding these back in.
SELECT `player`.`cid`, `player`.`k`, `player`.`d`, `gg`.`gg_id`, `gg`.`name`, `gg`.`img`, `cc`.`cid`, `cc`.`name`, `cc`.`class`, `cc`.`gg_id`
FROM `player`
LEFT JOIN `cc` ON `cc`.`cid` = `player`.`cid`
LEFT JOIN `gg` ON `gg`.`gg_id` = `cc`.`gg_id`
ORDER BY (`k`-`d`) DESC
i want to order by the K minus the D values, but im not getting it correctly
what im a doing wrong? with or without DESC/ASC, its wrong
Try:
SELECT (player.k-player.d), player.cid, player.k, player.d, gg.gg_id, gg.name, gg.img, cc.cid, cc.name, cc.class, cc.gg_idFROM player LEFT JOIN cc ON cc.cid = player.cid LEFT JOIN gg ON gg.gg_id = cc.gg_id ORDER BY (player.k-player.d) DESC
I did a quick query of my own and the results appear to be unordered (despite the fact the were) until I added the SELECT (player.k-player.d). MySQL also complained about ommiting the table name in the ORDER BY clause.