I want to limit the results in a lateral join, so that it only returns the N most recent matches.
This is my query, but the limit inside the join does not seem to work, as it returns all visitors
select am.id, am.title, ame.event, array_agg(row_to_json(visitors))
from auto_messages am
left join apps a on am.app_id = a.id
left join app_users au on a.id = au.app_id
left join auto_message_events ame on ame.auto_message_id = am.id
left join lateral (
select
id,
name,
avatar,
ame.inserted_at
from visitors v
where v.id = ame.visitor_id
order by ame.inserted_at desc
limit 1
) as visitors on visitors.id = ame.visitor_id
where am.id = '100'
group by am.id, ame.event
I am pretty sure the problem is with ame. That is where the rows are generated. The join to visitors is only picking up additional information.
So, this might solve your problem:
select am.id, am.title, visitors.event, array_agg(row_to_json(visitors))
from auto_messages am left join
apps a
on am.app_id = a.id left join
app_users au
on a.id = au.app_id left join lateral
(select v.id, v.name, v.avatar,
ame.event, ame.inserted_at, ame.auto_message_id
from auto_message_events ame join
visitors v
on v.id = ame.visitor_id
order by ame.inserted_at desc
limit 1
) visitors
on visitors.auto_message_id = am.id
where am.id = '100'
group by am.id, visitors.event;
You also might want to change your select clause, if you only want a subset of columns.
Related
I am working with sql server through SSMS right now. How can i choose all people with multiple(>2)vacancies?
I am trying something like that, but i dont understand how to make part with "more than 2 vacancies"?
SELECT dbo.applicants.FirstName, dbo.vacancy.Name
FROM dbo.applicants INNER JOIN
dbo.VacancyApplicant ON dbo.applicants.id = dbo.VacancyApplicant.ApplicantId INNER JOIN
dbo.vacancy ON dbo.VacancyApplicant.VacancyId = dbo.vacancy.id WHERE dbo.vacancy.Name='third vacancy'
SELECT dbo.applicants.FirstName, dbo.vacancy.Name
FROM dbo.applicants A INNER JOIN
dbo.VacancyApplicant V ON A.id = V.ApplicantId
WHERE EXIST(
SELECT 1
FROM dbo.applicants INNER JOIN
dbo.VacancyApplicant ON dbo.applicants.id =
dbo.VacancyApplicant.ApplicantId INNER JOIN
dbo.vacancy ON dbo.VacancyApplicant.VacancyId = dbo.vacancy.id
WHERE A.id=dbo.applicants.id
GROUP BY dbo.applicants.id,dbo.vacancy.id
HAVING COUNT(1)>2
)
Group By and Having are you basic answer. Below is a simple solution, might not be ideal, but can give you the idea.
I am finding target "applicants" ids in subquery, that uses GROUP BY and HAVING then outer query joins to that to output FirstName and LastName of applicant
SELECT dbo.applicants.FirstName, dbo.applicants.LastName FROM
dbo.applicants a INNER JOIN
(
SELECT dbo.applicants.id
FROM dbo.applicants INNER JOIN
dbo.VacancyApplicant ON dbo.applicants.id = dbo.VacancyApplicant.ApplicantId INNER JOIN
dbo.vacancy ON dbo.VacancyApplicant.VacancyId = dbo.vacancy.id AND dbo.vacancy.Name='third vacancy'
GROUP BY dbo.applications.id
HAVING COUNT(dbo.vacancy.id) > 2
) targetIds ON a.id = targetIds.id
"more than 2 vacancies"?
Your question only mentions vacancies but your query is filtering for a particular name. I assume you really want more than two of that name.
If I understand correctly, you want aggregation:
SELECT a.FirstName, a.Name
FROM dbo.applicants a INNER JOIN
dbo.VacancyApplicant va
ON a.id = va.ApplicantId INNER JOIN
dbo.vacancy v
ON va.VacancyId = v.id
WHERE v.Name = 'third vacancy'
GROUP BY a.FirstName, v.Name
HAVING COUNT(*) > 2;
Note the use of table aliases. They make the query easier to write and to read.
WITH TempCTE AS (
SELECT DISTINCT ap.FirstName
,vc.Name
,COUNT (va.VacancyId) OVER (PARTITION BY ap.id) AS NoOfVacancies
FROM dbo.applicants ap
JOIN dbo.VacancyApplicant va
ON ap.id = va.ApplicantId
JOIN dbo.vacancy vc
ON va.VacancyId = vc.id
)
SELECT FirstName,[Name], NoOfVacancies FROM TempCTE
WHERE NoOfVacancies > 2
I am trying to create one single query that will give me a distinct count for both the ActivityID and the CommentID. My query in MS Access looks like this:
SELECT
tbl_Category.Category, Count(tbl_Activity.ActivityID) AS CountOfActivityID,
Count(tbl_Comments.CommentID) AS CountOfCommentID
FROM tbl_Category LEFT JOIN
(tbl_Activity LEFT JOIN tbl_Comments ON
tbl_Activity.ActivityID = tbl_Comments.ActivityID) ON
tbl_Category.CategoryID = tbl_Activity.CategoryID
WHERE
(((tbl_Activity.UnitID)=5) AND ((tbl_Comments.PeriodID)=1))
GROUP BY
tbl_Category.Category;
I know the answer must somehow include SELECT DISTINCT but am not able to get it to work. Do I need to create multiple subqueries?
This is really painful in MS Access. I think the following does what you want to do:
SELECT ac.Category, ac.num_activities, aco.num_comments
FROM (SELECT ca.category, COUNT(*) as num_activities
FROM (SELECT DISTINCT c.Category, a.ActivityID
FROM (tbl_Category as c INNER JOIN
tbl_Activity as a
ON c.CategoryID = a.CategoryID
) INNER JOIN
tbl_Comments as co
ON a.ActivityID = co.ActivityID
WHERE a.UnitID = 5 AND co.PeriodID = 1
) as caa
GROUP BY ca.category
) as ca LEFT JOIN
(SELECT c.Category, COUNT(*) as num_comments
FROM (SELECT DISTINCT c.Category, co.CommentId
FROM (tbl_Category as c INNER JOIN
tbl_Activity as a
ON c.CategoryID = a.CategoryID
) INNER JOIN
tbl_Comments as co
ON a.ActivityID = co.ActivityID
WHERE a.UnitID = 5 AND co.PeriodID = 1
) as aco
GROUP BY c.Category
) as aco
ON aco.CommentId = ac.CommentId
Note that your LEFT JOINs are superfluous because the WHERE clause turns them into INNER JOINs. This adjusts the logic for that purpose. The filtering is also very tricky, because it uses both tables, requiring that both subqueries have both JOINs.
You can use DISTINCT:
SELECT
tbl_Category.Category, Count(DISTINCT tbl_Activity.ActivityID) AS CountOfActivityID,
Count(DISTINCT tbl_Comments.CommentID) AS CountOfCommentID
FROM tbl_Category LEFT JOIN
(tbl_Activity LEFT JOIN tbl_Comments ON
tbl_Activity.ActivityID = tbl_Comments.ActivityID) ON
tbl_Category.CategoryID = tbl_Activity.CategoryID
WHERE
(((tbl_Activity.UnitID)=5) AND ((tbl_Comments.PeriodID)=1))
GROUP BY
tbl_Category.Category;
SELECT l.LocID, COUNT(ulr.UserID)
FROM Locations l
LEFT OUTER JOIN UserLocationRights ulr ON l.LocID = ulr.LocID
LEFT OUTER JOIN Devices d ON l.LocID = d.LocID
LEFT OUTER JOIN UserModelRights umr ON d.ModelName = umr.ModelName
AND ulr.UserID = umr.UserID
GROUP BY l.LocID, ulr.UserID, d.ModelName
ORDER BY l.LocID, ulr.UserID
I want the results to be the LocID of all of the entries in Locations and the second column to be the number of Users who have rights to this location that also have the rights to at least one of the Devices in the Location which is determined by the entries in UserModelRights.
I can only figure out how to get what I want like this:
SELECT l.LocID, IsNull(UserHasModelRightInLoc.UserCount, 0) UserCount
FROM Locations l
LEFT OUTER JOIN (
SELECT ulr.LocID, COUNT(UserModelRightsPerLocation.UserID) UserCount
FROM UserLocRights ulr
INNER JOIN (
SELECT l.LocID, umr.UserID
FROM UserModelRights umr
INNER JOIN Devices d ON umr.ModelName = d.ModelName
INNER JOIN Locations l ON d.LocID = l.LocID
GROUP BY umr.ModelName, umr.UserID, l.LocID
) UserModelRightsPerLocation ON ulr.LocID = UserModelRightsPerLocation.LocID
AND ulr.UserID = UserModelRightsPerLocation.UserID
GROUP BY ulr.LocID
) UserHasModelRightInLoc ON l.LocID = UserHasModelRightInLoc.LocID
ORDER BY l.LocID
I don't know if this is possible, but I assume that there could be a way to use GROUP BY to get what I want using my first, much smaller query. The issue is that I think I need to do multiple GROUP BY in a specific order and I don't know if that's possible or makes sense in SQL.
Is there a way to get the result I want without using an aggregate function? If not, maybe narrow it down to a single one?
I find this a bit hard to follow without sample data. But based on your description, this might do what you want:
SELECT l.LocID, COUNT(DISTINCT ulr.UserID)
FROM Locations l LEFT JOIN
UserLocationRights ulr
ON l.LocID = ulr.LocID LEFT JOIN
Devices d
ON l.LocID = d.LocID LEFT JOIN
UserModelRights umr
ON d.ModelName = umr.ModelName AND
ulr.UserID = umr.UserID
GROUP BY l.LocID
ORDER BY l.LocID;
It needs receiving unique profiles ordered by creation_date. There is following query:
SELECT DISTINCT profiles.id, COALESCE(occured_at, users_visitors.created_at, visitors.created_at) creation_date FROM "profiles"
JOIN "visitors" ON "visitors"."profile_id" = "profiles"."id"
LEFT JOIN events ON profiles.id = events.profile_id
LEFT JOIN event_kinds ON event_kinds.id = events.event_kind_id
LEFT JOIN users_visitors ON visitors.id = users_visitors.visitor_id
WHERE (event_kinds.name = 'enter') AND "users_visitors"."user_id" = 2
ORDER BY creation_date asc
DISTINCT ON (profiles.id) won't help once it should be used for ordering. GROUP BY profiles.id, ... doesn't work as well.
Could you help me, please?
Does this GROUP BY work? Or which creation_date do you want - if not the max one?
SELECT profiles.id,
MAX(COALESCE(occured_at,
users_visitors.created_at,
visitors.created_at)) creation_date
FROM "profiles"
JOIN "visitors" ON "visitors"."profile_id" = "profiles"."id"
LEFT JOIN events ON profiles.id = events.profile_id
LEFT JOIN event_kinds ON event_kinds.id = events.event_kind_id
AND event_kinds.name = 'enter'
LEFT JOIN users_visitors ON visitors.id = users_visitors.visitor_id
AND "users_visitors"."user_id" = 2
GROUP BY profiles.id
ORDER BY creation_date asc
Note how I've moved the where clause conditions to get the LEFT JOIN's to perform as LEFT JOIN's.
I have a query like this:
SELECT m...., a...., r....
FROM 0_member AS m
LEFT JOIN 0_area AS a ON a.user_id = (SELECT user_id
FROM `0_area`
WHERE user_id = m.id
ORDER BY sec_id ASC LIMIT 1)
LEFT JOIN 0_rank as r ON a.rank_id = r.id
WHERE m.login_userid = '$username'
The idea is to get the first row from 0_area table and hence the attempted inner join. However, it is not working as expected.
Between 0_area and 0_member, 0_member.id = 0_area.user_id. However, there are multiple rows of 0_area.user_id and I want the row having the lowest value of sec_id.
Any help please?
SELECT m...., a...., r....
FROM 0_member AS m
LEFT JOIN (SELECT user_id, min(sec_id) minsec
FROM `0_area`
GROUP BY user_id) g1 on g1.user_id=m.id
LEFT JOIN 0_area AS a ON a.user_id = g1.user_id and a.sec_id=minsec
LEFT JOIN 0_rank as r ON a.rank_id = r.id
WHERE m.login_userid = '$username'