How could I count rows from a SELECT query as a value?
Such as
SELECT FUCNTIONIMLOOKINGFOR(SELECT * FROM anothertable) AS count FROM table;
So that count is an integer of how many rows the subquery SELECT * FROM anothertable returns.
EDIT
SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep,
(
SELECT COUNT(f.FlagTime)
FROM Flags as f
JOIN Posts as p
ON p.PostPID = f.FlagPID
) as PostFlags
FROM Posts AS p
JOIN Users AS u
ON p.PostUID = u.UserUID
ORDER BY PostTime DESC
LIMIT 0, 30
SELECT ( SELECT COUNT(id) FROM aTable ) as count FROM table
I assume your example is a truncated version of your actual query, so perhaps you should post what you are after to get a, possibly, more optimal query.
EDIT
Working directly from my brain, something like this should be more optimal.
SELECT p.PostPID, p.PostUID, p.PostText, p.PostTime, u.UserUID, u.UserName, u.UserImage, u.UserRep, COUNT(v.FlagTime) as postFlags
FROM Flags as f
JOIN Posts as p ON p.PostPID = f.FlagPID
JOIN Users AS u ON p.PostUID = u.UserUID
LIMIT 0, 30
GROUP BY p.PostPID
ORDER BY PostTime DESC
You can say
SELECT COUNT(*) FROM anothertable
which will return a numeric value, which you can use in another query, such as in the select list of another query, or as a condition in another query.
SELECT someVariable FROM table
WHERE (SELECT COUNT(*) FROM anotherTable) > 5
OR
SELECT someVariable, (SELECT COUNT(*) FROM anotherTable) as count FROM table
Related
Server won't byte on this query, it takes too long to execute:
select prodavac.id, count(artikl.id) as brojartikala, count(poruceno.id) as brojporudzbina from prod_prodavac prodavac
inner join prod_artikl artikl
on prodavac.id=artikl.prodavacid
inner join prod_poruceno poruceno
on prodavac.id=poruceno.prodavacid
group by prodavac.id
On the other hand, both semi-queries run mega fast:
select prodavac.id, count(artikl.id) as brojartikala from prod_prodavac prodavac
inner join prod_artikl artikl
on prodavac.id=artikl.prodavacid
group by prodavac.id
Also the other one:
select prodavac.id, count(poruceno.id) as brojporudzbina from prod_prodavac prodavac
inner join prod_poruceno poruceno
on prodavac.id=poruceno.prodavacid
group by prodavac.id
order by prodavac.id asc
I would really like to do it in one query, so how to merge them correct way? All IDs are indexed integers.
Explain select shows this:
Depending on the relations between the tables and the data, your combined query might not even return the desired result. For a simple count of relations you can use correlated subqueries in the SELECT clause:
select prodavac.id, (
select count(*)
from prod_artikl artikl
where artikl.prodavacid = prodavac.id
) as brojartikala, (
select count(*)
from prod_poruceno poruceno
where poruceno.prodavacid = prodavac.id
) as brojporudzbina
from prod_prodavac prodavac
order by prodavac.id asc
I have such a query:
SELECT
*,
(
SELECT COUNT(DISTINCT client_id)
FROM 1097_course_students_tbl
WHERE course_cycl_id=id
AND stts_id <> 8
AND client_id IN(SELECT id FROM 1097_clients_tbl WHERE is_removed=0)
) AS cnt
FROM 1097_course_cycle_tbl
WHERE (course_id IN (SELECT id FROM 1097_courses_tbl WHERE is_removed=2))
ORDER BY start_date DESC
I need to make it more efficient because it takes too long
any suggestions ?
thanks
Try the following
SELECT cc.*,IFNULL(q.cnt,0) cnt
FROM 1097_course_cycle_tbl cс
JOIN 1097_courses_tbl с ON c.id=cc.course_id AND c.is_removed=2
LEFT JOIN
(
SELECT cs.course_cycl_id,COUNT(DISTINCT cs.client_id) cnt
FROM 1097_course_students_tbl cs
JOIN 1097_clients_tbl c ON cs.client_id=c.id AND c.is_removed=0
WHERE cs.stts_id<>8
GROUP BY cs.course_cycl_id
) q
ON q.course_cycl_id=cс.id
ORDER BY cc.start_date DESC
I think id in 1097_courses_tbl and 1097_clients_tbl is primary key.
Therefore I replaced IN into JOIN.
And I converted the subquery from SELECT block wich executed for each rows into the subquery with GROUP BY which using in LEFT JOIN. Here it'll execute only one time and return all the necessary information.
The following query always outputs SUM for all rows instead of per userid. Not sure where else to look. Please help.
SELECT * FROM assignments
LEFT JOIN (
SELECT SUM(timeworked) AS totaltimeworked
FROM time_entries
) assignments ON (userid = assignments.userid AND ticketid = ?)
WHERE ticketid = ?
ORDER BY assigned,scheduled
If you want to keep the SELECT *, you would have to add a group by clause in the subquery. Something like this
SELECT * FROM assignments
LEFT JOIN (
SELECT SUM(timeworked) AS totaltimeworked
FROM time_entries
GROUP BY userid
) time_entriesSummed ON time_entriesSummed.userid = assignments.userid
WHERE ticketid = ?
ORDER BY assigned,scheduled
But a better way would be to change the SELECT * to instead select the fields you want a add a group by clause directly. Something like this
SELECT
assignments.id,
assignments.assigned,
assignments.scheduled,
SUM(time_entries.timeworked) AS totalTimeworked
FROM assignments
LEFT JOIN time_entries
ON time_entries.userid = assignments.userid
GROUP BY assignments.id, assignments.assigned, assignments.scheduled
Edit 1
Included table names in query 2 as mentioned in chameera's comment below
Doing a query on forum database. I am using this query to get thread name, poster, date etc.
(Left only thread_subject for now)
SELECT `thread_subject` FROM `fusion_posts` JOIN `fusion_threads`
ON fusion_posts.thread_id=fusion_threads.thread_id JOIN `fusion_users` ON
fusion_posts.post_author=fusion_users.user_id
GROUP BY fusion_posts.thread_id ORDER BY `post_id` DESC LIMIT 16
Basically, I also need to add something like the count below to the existing select, to count posts of each thread.
SELECT COUNT(*) AS PostCount FROM fusion_posts,fusion_threads WHERE fusion_threads.thread_id = fusion_posts.thread_id group by fusion_threads.thread_id
How could I do that?
Try this:-
SELECT `thread_subject`, COUNT(*) AS PostCount
FROM `fusion_posts` JOIN `fusion_threads`
ON fusion_posts.thread_id=fusion_threads.thread_id JOIN `fusion_users`
ON fusion_posts.post_author=fusion_users.user_id
GROUP BY fusion_posts.thread_id, `thread_subject`
ORDER BY `post_id` DESC
LIMIT 16
I have the following query, but after some time when users start putting in more and more items in the "ci_falsepositives" table, it gets really slow.
The ci_falsepositives table contains a reference field from ci_address_book and another reference field from ci_matched_sanctions.
How can I create a new query but still being able to sort on each field.
For example I can still sort on "hits" or "matches"
SELECT *, matches - falsepositives AS hits
FROM (SELECT c.*, IFNULL(p.total, 0) AS matches,
(SELECT COUNT(*)
FROM ci_falsepositives n
WHERE n.addressbook_id = c.reference
AND n.sanction_key IN
(SELECT sanction_key FROM ci_matched_sanctions)
) AS falsepositives
FROM ci_address_book c
LEFT JOIN
(SELECT addressbook_id, COUNT(match_id) AS total
FROM ci_matched_sanctions
GROUP BY addressbook_id) AS p
ON c.id = p.addressbook_id
) S
ORDER BY folder asc, wholename ASC
LIMIT 0,15
The problem has to be the SELECT COUNT(*) FROM ci_falsepositives sub-query. That sub-query can be written using an inner join between ci_falsepositives and ci_matched_sanctions, but the optimizer might do that for you anyway. What I think you need to do, though, is make that sub-query into a separate query in the FROM clause of the 'next query out' (that is, SELECT c.*, ...). Probably, that query is being evaluated multiple times - and that's what's hurting you when people add records to ci_falsepositives. You should study the query plan carefully.
Maybe this query will be better:
SELECT *, matches - falsepositives AS hits
FROM (SELECT c.*, IFNULL(p.total, 0) AS matches, f.falsepositives
FROM ci_address_book AS c
JOIN (SELECT n.addressbook_id, COUNT(*) AS falsepositives
FROM ci_falsepositives AS n
JOIN ci_matched_sanctions AS m
ON n.sanction_key = m.sanction_key
GROUP BY n.addressbook_id
) AS f
ON c.reference = f.addressbook_id
LEFT JOIN
(SELECT addressbook_id, COUNT(match_id) AS total
FROM ci_matched_sanctions
GROUP BY addressbook_id) AS p
ON c.id = p.addressbook_id
) AS s
ORDER BY folder asc, wholename ASC
LIMIT 0, 15