I have two tables: users and photos.
Users have many photos. Photos have a column called user_id, photos have one user. Photos also have a column called reported which is 0 or 1.
I need to know the number of users who have at least 1 photo with reported = 1. I also need to get the number of users who have at least 2 photos with reported = 1.
How would I do this? Here's what I'd like to do, but it obviously doesn't work:
select count(*)
from users join
(select * from photos where photos.reported = 1) as p2
on users.photo_id = p2.id;
This is at least 1
select count(distinct userid)
from photos
where reported = 1
This is at least 2.
select count(distinct userid)
from photos
where reported = 1
group by userid
having count(userid) > 2
Just get a histogram of the counts:
select numreported, count(*), min(user_id), max(user_id)
from (select p.user_id, sum(p.reported = 1) as numreported
from photos p
group by p.user_id
) p
group by numreported
order by numreported;
This gives you the number of users that have all counts of numreported, including 0.
Something like the following should work
select count(hasOne) cntHasOne, count(hasTwo) cntHasTwo from
(select users.user_id, 1 hasOne,
case when count(*) > 1 then 1 else 0 end hasTwo
from users inner join solution on(users.user_id = solution.user_id)
where solution.winning_status = 1
group by user_id) T1
Related
Im newbie please help me on my project. I have 2 tables below.
Table user:
Table Likes
I want to count all likes per story_id and check if the given user has like the story else it will return null.
as of now this is my query and output, given user id = 1.
SELECT COUNT(*) , sl.story_id, u.id as user
FROM stories_likes sl
LEFT JOIN users u ON sl.user_id = u.id AND sl.user_id = 1
GROUP BY sl.story_id
My output:
But what i want to get output is:
Given: user_id = 1
Given user_id = 4
Sorry for the construction of my question i dont know how. Thanks in advance
If the query should display the result for a one particular user_id only then try the following query:
select count(*),
story_id,
(case find_in_set(1, Group_concat(user_id separator ',')) >0 then 1
else NULL
end
)as user_id
from Stories_Likes
group by story_id;
In above query, you can put user_id manually after when, or you can set a variable with particular Id and use it in the query.
For i.e., if you want to check for user_id=4, then put 4 after when and then.
Click here for the Updated Demo
Hope it helps!
The users table is left joined to the query, so it may have null values. Instead, you should use the user_id column from the stories_likes table:
SELECT COUNT(*) , sl.story_id, sl.user_id as user
-- Here --------------------------^
FROM stories_likes sl
LEFT JOIN users u ON sl.user_id = u.id AND sl.user_id = 1
GROUP BY sl.story_id
Got the answer. for those who has the same problem and needed this here's the answer.
SELECT COUNT(*) , sl.story_id, t.user_id
FROM stories_likes sl
LEFT JOIN users u ON sl.user_id = u.id
LEFT JOIN (SELECT * FROM stories_likes WHERE user_id = 4) t ON
sl.story_id = t.story_id
GROUP BY sl.story_id
Where the given user is declared on temporary table t
I have 2 tables: user and review, a one-to-many relationship.
When I execute the following query:
SELECT
user_id,
count(*) totalReviews,
USER . NAME
FROM
review,
USER
WHERE
USER .id = review.user_id
GROUP BY
user_id
I get:
1 2 marius
2 2 daniela
3 1 alin
What I want to do now is to display first 2 users because they have given the most reviews(2).
I tried adding having, if I hardcode having totalReviews=2 it works, but if I write having total = max(total) I get 0 results, while if I'm trying with,
SELECT
*
FROM
(
SELECT
user_id,
count(*) total,
USER . NAME
FROM
review,
USER
WHERE
USER .id = review.user_id
GROUP BY
user_id
) A
WHERE
total = (SELECT max(total) FROM A) `
I get an error (table A doesn't exist)
You would do this with ORDER BY and LIMIT:
SELECT u.id, count(*) as totalReviews, u.name
FROM review r JOIN
user u
ON u.id = r.user_id
GROUP BY u.id, u.name
ORDER BY totalReviews DESC
LIMIT 2;
Notes:
Never use commas in the FROM clause. Always use proper, explicit JOIN syntax.
Table aliases make the query easier to write and read.
EDIT:
If occurs to me that you want all users with the maximum number of reviews, not exactly 2. Here is one method:
SELECT u.id, COUNT(*) as totalReviews, u.name
FROM review r JOIN
user u
ON u.id = r.user_id
GROUP BY u.id, u.name
HAVING totalReviews = (SELECT COUNT(*)
FROM review r2
GROUP BY r2.user_id
ORDER BY COUNT(*) DESC
LIMIT 1
);
Note that the subquery in the HAVING clause is simpler than the outer query. There is no need to bring in the user name.
This query:
SELECT
user_id,
count(base_item)
FROM items
WHERE base_item = '202'
group by user_id order by count(base_item)
Gives me this result:
which I want.
However, I also want it to exclude all user ids in the users table with a rank of 5 or greater. as shown here
Modify your where clause this way:
WHERE base_item = '202' AND user_id NOT IN (SELECT id FROM users WHERE rank > 5)
The portion in parentheses is called a subquery. The result set of the subquery contains the id of all users with a rank greater than 5. The addition to the where clause excludes all users in that result set.
Join with the users table and filter out rows with high rank
SELECT user_id, count(*) AS count
FROM items AS i
JOIN users AS u ON i.user_id = u.id
WHERE i.base_item = '202'
AND u.rank <= 5
group by user_id
order by count
I am creating a mobile application that need to synchronize with the server, and In order to do so, I need to get last (N) messages in each conversation.
note that this query was worked but get only last message in each conversation.
SELECT users.user_id AS user_id,
users.username,
users.picture,
users.last_seen,
me.message,
me.created_on
FROM messages me,
users
WHERE (me.sender_id=1
OR me.recipient_id=1)
AND ((me.sender_id=user_id
AND me.sender_id<>1)
OR (me.recipient_id=user_id
AND me.recipient_id<>1))
AND NOT exists
(SELECT 1
FROM messages me2
WHERE me2.id>me.id
AND ((me.sender_id=me2.sender_id
AND me.recipient_id=me2.recipient_id)
OR (me.sender_id=me2.recipient_id
AND me.recipient_id=me2.sender_id)))
ORDER BY me.created_on DESC
First we get all messages of all users ordered by user and date. We introduce artificial vars to number messages of user. When user id is the same we just increase message number. If it's different reset it to 0.
Thus subquery returns us
user_id, mess_n
1 0
1 1
1 2
2 0
2 1
2 2
3 0
3 1
3 2
Then in the query just leave messages with number <10 (first 10)
select *
from (
select u.*, m.*,
#mess_n_for_user:=if(u.user_id!=#curr_user,0,#mess_n_for_user+1) as mess_n,
#curr_user:=u.user_id
from (SELECT #mess_n_for_user:=0, #curr_user:=-1) sess_var,
users u join messages m on (u.user_id=m.sender_id
or u.user_id=m.recipient_id)
order by u.user_id, m.created_on DESC) all_messages_ordered
where all_messages_ordered.mess_n<10
Just add all filters conditions to the query
UPDATED
FROM the sqlfiddle
select * from (
select all_messages_ordered.*,
#mess_n_for_user:=if(u_id!=#curr_user,0,#mess_n_for_user+1) as mess_n,
#curr_user:=u_id
from (SELECT #mess_n_for_user:=0, #curr_user:=-1) sess_var,
(
select u.id as u_id, u.first_name, m.*
from
accounts u join messages m on (u.id=m.from or u.id=m.to)
and (m.to=1 or m.from=1)
and u.id<>1
order by u.id, m.date_time DESC) all_messages_ordered) a
where mess_n<3
You need a recursive query to select conversations. Following the approach from this answer, substituting recipient_id / sender_id for col3 / col1 :
select id, recipient_id, #pv:=sender_id as 'recipient_id' from messages
join
(select #pv:=2)tmp
where recipient_id=#pv
I have not tested this but the principle should be correct. Of course you will need to expand this to fully solve your problem...but hope this helps.
I am trying to write a query to find the score rank of a user's games. I need it to take in a user id and then return that user's relative ranking to other user's scores. There is a user and a game table. The game table has a userId field with a one-to-many relationship.
Sample table:
users:
id freebee
1 10
2 13
games:
userId score
1 15
1 20
2 10
1 15
passing $id 1 into this function should return the value 1, as user 1 currently has the highest score. Likewise, user 2 would return 2.
Currently this is what I have:
SELECT outerU.id, (
SELECT COUNT( * )
FROM users userI, games gameI
WHERE userI.id = gameI.userId
AND userO.id = gameO.userId
AND (
userI.freebee + SUM(gameI.score)
) >= ( userO.freebee + SUM(gameO.score) )
) AS rank
FROM users userO,
games gameO
WHERE id = $id
Which is giving me an "invalid use of group function" error. Any ideas?
SELECT u.id,total_score,
( SELECT COUNT(*) FROM
(SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId = u1.id)
GROUP BY u1.id
)x1
WHERE x1.total_score > x.total_score
)+1 as rank,
( SELECT COUNT(DISTINCT total_score) FROM
(SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId_Id = u1.id)
GROUP BY u1.id
)x1
WHERE x1.total_score > x.total_score
)+1 as dns_rank
FROM users u
LEFT JOIN
( SELECT u1.id, (IFNULL(u1.freebee,0)+ IFNULL(SUM(score),0)) as total_score
FROM users u1
LEFT JOIN games g ON (g.userId = u1.id)
GROUP BY u1.id
)x ON (x.id = u.id)
rank - (normal rank - e.g. - 1,2,2,4,5), dns_rank - dense rank (1,2,2,3,4). Column total_score - just for debugging...
The query does not like the reference of an outer table in the Sum function SUM(gameO.score) in the correlated subquery. Second, stop using the comma format for joins. Instead use the ANSI syntax of JOIN. For example, in your outer query did you really mean to use a cross join? That is how you wrote and how I represented it in the solution below but I doubt that is what you want.
EDIT
I've adjusted my query given your new information.
Select U.id, U.freebee, GameRanks.Score, GameRanks.Rank
From users As U
Join (
Select G.userid, G.score
, (
Select Count(*)
From Games As G2
Where G2.userid = G.userid
And G2.Score > G.Score
) + 1 As Rank
From Games As G
) As GameRanks
On GameRanks.userid = U.id
Where U.id =1
I'm not a MySQL person, but I believe that the usual way to do ranking in it is using a variable within your SQL statement. Something like the below (untested):
SELECT
SQ.user_id,
#rank:=#rank + 1 AS rank
FROM
(
SELECT
U.user_id,
U.freebee + SUM(COALESCE(G.score, 0)) AS total_score
FROM
Users U
LEFT OUTER JOIN Games G ON
G.user_id = U.user_id
) SQ
ORDER BY
SQ.total_score DESC
You could use that as a subquery to get the rank for a single user, although performance-wise that might not be the best route.
Here is "simplified" version for calculating a rank based only on "games" table. For calculating rank for a specific game only you need to add additional joins.
SELECT COUNT(*) + 1 AS rank
FROM (SELECT userid,
SUM(score) AS total
FROM games
GROUP BY userid
ORDER BY total DESC) AS gamescore
WHERE gamescore.total > (SELECT SUM(score)
FROM games
WHERE userid = 1)
It's based on the idea that ranking == number of players with bigger score + 1
Check this out:
http://rpbouman.blogspot.com/2009/09/mysql-another-ranking-trick.html