I have a LEFT JOIN query
SELECT
a.id_user,b.id_post, COUNT(a.*) as total_users
FROM
posts as b
LEFT JOIN .....
LEFT JOIN .....
WHERE ....
ORDER BY .....
GROUP BY
a._id_user
LIMIT 3,10
If I use COUNT(a.*) AS total_users to retrieve the number of users, but I get an error; what would be the correct syntax?
The syntax should look more like:
SELECT a.?, COUNT(b.?) as total_users
FROM a LEFT JOIN
b
ON . . .
GROUP BY a.?
you need a group by
select a.id_user, b.id_post, count(1)
from.....
group by a.id_user, b.id_post
You can either Count([some specific field]) or Count(*), but as Gordon Linoff correctly stated, you cannot typically use Count(alias.*)
The Count() function expects an expression ( a single value ). For each row where the expression is not NULL, that row will be counted. Count(*) is a special case returning the number of rows in the result set.
Following returns all posts and counts number of users somehow joined to these posts (there is no info about this in your question)
SELECT
a.id_user,
b.id_post,
COUNT(DISTINCT a.id_user) as total_users
Related
I have query below as
select t.comment_count, count(*) as frequency
from
(select u.id, count(c.user_id) as comment_count
from users u
left join comments c
on u.id = c.user_id
and c.created_at between '2020-01-01' and '2020-01-31'
group by 1) t
group by 1
order by 1
when I also try to alias the count(*) as count(t.*) it gives error, can I not alias that with the t from the table? Not sure what I am missing
Thank you
Count(*) stands for the count of all rows returned by a query (with respect to GROUP BY columns). So it makes no sence to specify one of the involved tables. Consider counting rows produced by a join for example. If you need a count of rows of the specific table t you can use count(distinct t.<unique column>)
I want to check that an amount of likes the users received in all their personal pictures is at least twice as large as the number of likes received in the group pictures in which they are tagged.
In case the user is not tagged in any group photo but is tagged in a personal picture that has received at least one like, it will be returned.
My Question is:
How can I make a comparison between 2 sum functions
Where one result of the sum is returned in the nested query and compared with the external query.
Can I set an auxiliary variable to enter the sum value in it and compare it?
Thanks for the helpers:)
Select distinct UIP.userID
From tblUserInPersonalPic UIP
where **sum(UIP.numOfLikes) over (Partition by UIP.userID)*0.5** >
(Select distinct U.userID, sum(P.numOfLikes) over (Partition by U.userID)
From tblgroupPictures P left outer join
tblUserInGroupPic U On P.picNum=U.picNum
group by U.userID,P.numOfLikes,P.picNum)
It's kinda hard to know for sure, and of course I can't test my answer,
but I think you can do it with a couple of left joins, group by and having:
SELECT Personal.UserId
FROM tblUserInPersonalPic Personal
LEFT JOIN tblUserInGroupPic UserInGroup ON Personal.userID = UserInGroup.UesrId
LEFT JOIM tblgroupPictures GroupPictures ON UserInGroup.picNum = GroupPictures.picNum
GROUP BY Personal.userID
HAVING SUM(GroupPictures.numOfLikes) * 2 < SUM(Personal.numOfLikes)
Please note: When posting sql questions it's always best to provide sample data as DDL + DML (Create table + insert into statements) and desired results, so that who ever answers you can test the answer before posting it.
Try using two ctes..pseudo code.Also note distinct in second query will not even work,since you are returning two columns,so i changed it it below,so that you can get that column as well
;with tbl1
as
(
select a,sum(col1) as summ
from
tbl1
)
,tbl2
as
(
select userid,sum(Anothersmcol) as sum2
from tbl2
)
select tbl1.columns,tbl2.columns
from
tbl1 t1
join
tbl2 t2
on t1.sumcol>t2.sumcol
You can't use window functions in a where clause. Define it in a subquery:
select *
from (
select sum(...) over (...) as Sum1
, OtherColumn
from YourTable
) sub
where Sum1 < (...your subquery...)
I need some help to join my tables, I used 2 tables
//table news
id_news|title|
1 |first..|
2 |second..|
//table comment
id_comment|content|id_news
1|Haha..|1
2|Hahe..|2
3|Hoho..|1
I need an output use COUNT(*) comments in id_news 1
like
id_news|title|total_comment|
1|first..|**2**|
so far my syntax like
SELECT
news.id_news,
COUNT(distinct comment.id_news)
FROM
news
inner join comment ON (comment.id_news=news.id_news)
group by
news.id_news
I think you want:
SELECT news.id_news, COUNT(*)
FROM news INNER JOIN
comment
ON comment.id_news = news.id_news
GROUP BY news.id_news;
Note the following:
The select clause uses the same column as the group by
The COUNT() is not using a distinct. In your formulation, it would always return 1, regardless of the number of comments.
If you want news items with no comments, you would use a left outer join and change the count(*) to count(comment.id_news).
Try This Query you will get the data as you want :
SELECT
news.id_news,news.title,
(select count(*) from comment group_by id_news) as total_comment
FROM
news
inner join comment ON comment.id_news=news.id_news
SELECT
DEPTMST.DEPTID,
DEPTMST.DEPTNAME,
DEPTMST.CREATEDT,
COUNT(USRMST.UID)
FROM DEPTMASTER DEPTMST
INNER JOIN USERMASTER USRMST ON USRMST.DEPTID=DEPTMST.DEPTID
WHERE DEPTMST.CUSTID=1000 AND DEPTMST.STATUS='ACT
I have tried several combination but I keep getting error
Column 'DEPTMASTER.DeptID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause
I also add group by but it's not working
WHen using count like that you need to group on the selected columns,
ie.
SELECT
DEPTMST.DEPTID,
DEPTMST.DEPTNAME,
DEPTMST.CREATEDT,
COUNT(USRMST.UID)
FROM DEPTMASTER DEPTMST
INNER JOIN USERMASTER USRMST ON USRMST.DEPTID=DEPTMST.DEPTID
WHERE DEPTMST.CUSTID=1000 AND DEPTMST.STATUS='ACT'
GROUP BY DEPTMST.DEPTID,
DEPTMST.DEPTNAME,
DEPTMST.CREATEDT
you miss group by
SELECT DEPTMST.DEPTID,
DEPTMST.DEPTNAME,
DEPTMST.CREATEDT,
COUNT(USRMST.UID)
FROM DEPTMASTER DEPTMST
INNER JOIN USERMASTER USRMST ON USRMST.DEPTID=DEPTMST.DEPTID
WHERE DEPTMST.CUSTID=1000 AND DEPTMST.STATUS='ACT
group by DEPTMST.DEPTID,
DEPTMST.DEPTNAME,
DEPTMST.CREATEDT
All aggregate functions like averaging, counting,sum needs to be used along with a group by function. If you dont use a group by clause, you are performing the function on all the rows of the table.
Eg.
Select count(*) from table;
This returns the count of all the rows in the table.
Select count(*) from table group by name
This will first group the table data based on name and then return the count of each of these groups.
So in your case, if you want the countof USRMST.UID, group it by all the other columns in the select list.
I have 3 tables, where the first one's primary key, is the foreign key in the other 2.
I want to extract one field from the first table, and then a count from the other 2, all joined using the pk and fk. This is what I have so far:
SELECT MBDDX_STUDY.STUDY_NAME, COUNT(MBDDX_EXPERIMENT.STUDY_ID) AS NUMBER_OF_EXPERIMENTS
FROM MBDDX_STUDY
INNER JOIN MBDDX_EXPERIMENT
ON MBDDX_STUDY.ID=MBDDX_EXPERIMENT.STUDY_ID
INNER JOIN (SELECT COUNT(MBDDX_TREATMENT_GROUP.GROUP_NO) AS NUMBER_OF_GROUPS
FROM MBDDX_TREATMENT_GROUP)
ON MBDDX_TREATMENT_GROUP.STUDY_ID = MBDDX_STUDY.ID
group by MBDDX_STUDY.STUDY_NAME, MBDDX_TREATMENT_GROUP.STUDY_ID
But, i get an error saying that the MBDDX_TREATMENT_GROUP.STUDY_ID , in the penultimate line is an invalid indentifier. It is a correct table.
Any advise please.
Thanks.
You're getting the error because that column is not in your SELECT, so it can't GROUP BY a field it doesn't have.
The subquery syntax doesn't seem to make any sense to me. You've made a query that counts all rows of MBDDX_TREATMENT_GROUP, independently of the STUDY_ID, and then tries to join it into the table with a join condition that doesn't refer to anything in the subquery's results (and can't, without an alias).
Why not use a simple join? Assuming MBDDX_EXPERIMENT also has a primary key ID, you can do it with a COUNT-DISTINCT:
SELECT
MBDDX_STUDY.ID, MBDDX_STUDY.STUDY_NAME,
COUNT(DISTINCT MBDDX_EXPERIMENT.ID) AS NUMBER_OF_EXPERIMENTS
COUNT(DISTINCT MBDDX_TREATMENT_GROUP.GROUP_NO) AS NUMBER_OF_GROUPS
FROM
MBDDX_STUDY
INNER JOIN MBDDX_EXPERIMENT ON MBDDX_EXPERIMENT.STUDY_ID=MBDDX_STUDY.ID
INNER JOIN MBDDX_TREATMENT_GROUP ON MBDDX_TREATMENT_GROUP.STUDY_ID=MBDDX_STUDY.ID
GROUP BY
MBDDX_STUDY.ID, MBDDX_STUDY.STUDY_NAME
(MBDDX_STUDY.STUDY_NAME technically shouldn't be necessary to include in the GROUP BY expression according to ANSI SQL as it has a functional dependency on STUDY_ID. However it is necessary on Oracle, which can't spot the dependency.)
You don't need to group by this field (MBDDX_TREATMENT_GROUP.STUDY_ID). It should be just group by MBDDX_STUDY.STUDY_NAME
If my understanding is correct,You need a record from first table and have the count of related records in the other two tables.Here is the answer
SQL:Getting count from many tables for a user record in USER table.Whats the best approach?
It looks like you need to alias the second subquery and need to include something to join on.
It also looks like you aren't using the count you have in the subquery as well.
Try this out:
SELECT MBDDX_STUDY.STUDY_NAME
, COUNT(MBDDX_EXPERIMENT.STUDY_ID) AS NUMBER_OF_EXPERIMENTS
FROM MBDDX_STUDY
INNER JOIN MBDDX_EXPERIMENT
ON MBDDX_STUDY.ID=MBDDX_EXPERIMENT.STUDY_ID
INNER JOIN (SELECT STUDY_ID, COUNT(MBDDX_TREATMENT_GROUP.GROUP_NO) AS NUMBER_OF_GROUPS
FROM MBDDX_TREATMENT_GROUP GROUP BY MBDDX_TREATMENT_GROUP.STUDY_ID) xx
ON xx.STUDY_ID = MBDDX_STUDY.ID
GROUP BY MBDDX_STUDY.STUDY_NAME, xx.STUDY_ID
For what you really want to do, you want OUTER JOINs.
WITH number_of_experiments
AS ( SELECT study_id
, count ( * ) CNT
FROM MBDDX_EXPERIMENT
group by study_id )
, number_of_groups
as ( select study_id
, count ( * ) CNT
FROM mbddx_treatment_group
group by study_id )
select study_name
, coalesce(noex.cnt,0)
, coalesce(notr.cnt,0)
from mbddx_study
outer join number_of_experiments
as noex
using ( study_id )
outer join number_of_groups
as nogr
using ( study_id )