Hi I'm new to SQL and I'm trying to figure out how I'm going to get the top 5 "bands" with most friends (userId) and this is what i have; a usertbl with userId as PK then a bandsTbl with bandId as PK then I have a table bandfriends with FK userId and bandId.
bandfriends
userid | bandId
---------------
1 | 1
1 | 2
1 | 3
Thanks!
SELECT TOP 5 bandId, fanCount
FROM
(SELECT bandId, COUNT(*) as fanCount
FROM bandfriends
GROUP BY bandId
ORDER BY COUNT(*) DESC)
You can also optionally specify WITH TIES in the select statement. See this and this.
select top 5 b.b_name, count(friends) as numOfFriends
from bands b inner join link l on b.b_id = l.bands inner join
friends f on f.f_id = l.friends
group by b.b_name
order by numOfFriends desc
If you have friends table, bands table and a link table, works for me :)
Read up on COUNT and GROUP BY at mysql.org
You'll want something like this (I haven't tested it):
SELECT bandId, COUNT(*) as fans FROM bandfriends
ORDER BY fans DESC
GROUP BY bandId
LIMIT 5;
Related
I'm having the following request to get all artworks inner join with their user info:
SELECT a.*, row_to_json(u.*) as users
FROM artworks a INNER JOIN users u USING(address)
WHERE (a.flag != "ILLEGAL" OR a.flag IS NULL)
ORDER BY a.date DESC
LIMIT 100
How could i have the same query but including no more than 3 entries per user?
Each user have a unique id called "address"
I think DISTINCT ON only work for 1 per user, maybe ROW_NUMBER?
Thank you in advance, i'm pretty new to DB queries.
You need an extra column in which you specify the nth time that the user is in the table. This will look something like this:
USER | N
user1 | 1
user1 | 2
user1 | 3
user2 | 1
user2 | 2
Getting the extra column in a new table can be done by using the following code
--Create new Table as T
WITH T AS (
SELECT TOP 100
a.*,
row_to_json(u.*) as users,
ROW_NUMBER() OVER(PARTITION BY u.user ORDER BY a.date DESC) AS N
FROM artworks a INNER JOIN users u USING(address)
WHERE (a.flag != "ILLEGAL" OR a.flag IS NULL) )
--Select columns from your new table
SELECT columns from T
WHERE (T.N =1 OR T.N =2 OR T.N =3)
Just an addition to your original query will do. Count the resulting records for each user and then filter by the counter value.
I am using users.address as the user id.
SELECT * from
(
SELECT a.*, row_to_json(u.*) as userinfo,
row_number() over (partition by u.address order by a.date desc) as ucount
FROM artworks a INNER JOIN users u ON a.address = u.address
WHERE a.flag != "ILLEGAL" OR a.flag IS NULL
) t
WHERE ucount <= 3
ORDER BY date DESC
LIMIT 100;
A remark - you have users as a column alias and as a table name which may cause confusion. I have changed the alias to userinfo.
I have two tables which look like this :-
Component Table
Revision Table
I want to get the name,model_id,rev_id from this table such that the result set has the data like shown below :-
name model_id rev_id created_at
ABC 1234 2 23456
ABC 5678 2 10001
XYZ 4567
Here the data is grouped by name,model_id and only 1 data for each group is shown which has the highest value of created_at.
I am using the below query but it is giving me incorrect result.
SELECT cm.name,cm.model_id,r.created_at from dummy.component cm
left join dummy.revision r on cm.model_id=r.model_id
group by cm.name,cm.model_id,r.created_at
ORDER BY cm.name asc,
r.created_at DESC;
Result :-
Anyone's help will be highly appreciated.
use max and sub-query
select T1.name,T1.model_id,r.rev_id,T1.created_at from
(
select cm.name,
cm.model_id,
MAX(r.created_at) As created_at from dummy.component cm
left join dummy.revision r on cm.model_id=r.model_id
group by cm.name,cm.model_id
) T1
left join revision r
on T1.created_at =r.created_at
http://www.sqlfiddle.com/#!17/68cb5/4
name model_id rev_id created_at
ABC 1234 2 23456
ABC 5678 2 10001
xyz 4567
In your SELECT you're missing rev_id
Try this:
SELECT
cm.name,
cm.model_id,
MAX(r.rev_id) AS rev_id,
MAX(r.created_at) As created_at
from dummy.component cm
left join dummy.revision r on cm.model_id=r.model_id
group by 1,2
ORDER BY cm.name asc,
r.created_at DESC;
What you were missing is the statement to say you only want the max record from the join table. So you need to join records, but the join will bring in all records from table r. If you group by the 2 columns in component, then select the max from r, on the id and created date, it'll only pick the top out the available to join
I would use distinct on:
select distinct on (m.id) m.id, m.name, r.rev_id, r.created_at
from model m left join
revision r
on m.model_id = r.model_id
order by m.id, r.rev_id;
How to find the user with the most referrals that have at least three blue shoes using PostgreSQL?
table 1 - users
name (matches shoes.owner_name)
referred_by (foreign keyed to users.name)
table 2 - shoes
owner_name (matches persons.name)
shoe_name
shoe_color
What I have so far is separate queries returning parts of what I want above:
(SELECT count(*) as shoe_count
FROM shoes
GROUP BY owner_name
WHERE shoe_color = “blue”
AND shoe_count>3) most_shoes
INNER JOIN
(SELECT count(*) as referral_count
FROM users
GROUP BY referred_by
) most_referrals
ORDER BY referral_count DESC
LIMIT 1
Two subqueries seem like the way to go. They would look like:
SELECT s.owner_name, s.show_count, r.referral_count
FROM (SELECT owner_name, count(*) as shoe_count
FROM shoes
WHERE shoe_color = 'blue'
GROUP BY owner_name
HAVING shoe_count >= 3
) s JOIN
(SELECT referred_by, count(*) as referral_count
FROM users
GROUP BY referred_by
) r
ON s.owner_name = r.referred_by
ORDER BY r.referral_count DESC
LIMIT 1 ;
Hi so i am trying to output the city with playerid with the most AB(runs).
Output the birth city of the player who had the most at bats (AB) in
his career.
Now i get what i want Cinncinati, sander01, 14432, this is correct. But it shows up in 3's like this. That too for every city and player and runs, like the 2nd most. I only need 1 entry, the other 2 are redundant. I think there something i did wrong with group by, any help? plz
Cinncinati, sander01, 14432
Cinncinati, sander01, 14432
Cinncinati, sander01, 14432
Chicago, dere90, 12324
Chicago, dere90, 12324
Chicago, dere90, 12324
SELECT a.bcity,a.id, b.ab FROM master a
JOIN
(SELECT id, SUM(ab) as ab FROM batting
GROUP by id) b
ON a.id = b.id
ORDER by b.ab DESC
limit 30;
Refer to DISTINCT for getting distinct result set.Now coming to your question,join master table with the top row from the result set b.
select a.bcity,b.id,b.ab from master a
join
(select id,sum(ab) as ab from batting
group by id
order by ab desc
limit 1
) b
on a.id = b.id
You can change the LIMIT 30 to LIMIT 1 and get the same result.
SELECT a.bcity,a.id, b.ab FROM master a
JOIN
(SELECT id, SUM(ab) as ab FROM batting
GROUP by id
) b
ON a.id = b.id
ORDER by b.ab DESC
limit 1;
Note: if there are multiple players with the same most runs then LIMIT 1 will not give the correct answer.
I have two tables, and am doing an ordered select on each of them. I wold like to see the results of both orders in one result.
Example (simplified):
"SELECT * FROM table1 ORDER BY visits;"
name|# of visits
----+-----------
AA | 5
BB | 9
CC | 12
.
.
.
"SELECT * FROM table2 ORDER BY spent;"
name|$ spent
----+-------
AA | 20
CC | 30
BB | 50
.
.
.
I want to display the results as two columns so I can visually get a feeling if the most frequent visitors are also the best buyers. (I know this example is bad DB design and not a real scenario. It is an example)
I want to get this:
name by visits|name by spent
--------------+-------------
AA | AA
BB | CC
CC | BB
I am using SQLite.
Select A.Name as NameByVisits, B.Name as NameBySpent
From (Select C.*, RowId as RowNumber From (Select Name From Table1 Order by visits) C) A
Inner Join
(Select D.*, RowId as RowNumber From (Select Name From Table2 Order by spent) D) B
On A.RowNumber = B.RowNumber
Try this
select
ISNULL(ts.rn,tv.rn),
spent.name,
visits.name
from
(select *, (select count(*) rn from spent s where s.value>=spent.value ) rn from spent) ts
full outer join
(select *, (select count(*) rn from visits v where v.visits>=visits.visits ) rn from visits) tv
on ts.rn = tv.rn
order by ISNULL(ts.rn,tv.rn)
It creates a rank for each entry in the source table, and joins the two on their rank. If there are duplicate ranks they will return duplicates in the results.
I know it is not a direct answer, but I was searching for it so in case someone needs it: this is a simpler solution for when the results are only one per column:
select
(select roleid from role where rolename='app.roles/anon') roleid, -- the name of the subselect will be the name of the column
(select userid from users where username='pepe') userid; -- same here
Result:
roleid | userid
--------------------------------------+--------------------------------------
31aa33c4-4e66-4da3-8525-42689e46e635 | 12ad8c95-fbef-4287-9834-7458a4b250ee
For RDBMS that support common table expressions and window functions (e.g., SQL Server, Oracle, PostreSQL), I would use:
WITH most_visited AS
(
SELECT ROW_NUMBER() OVER (ORDER BY num_visits) AS num, name, num_visits
FROM visits
),
most_spent AS
(
SELECT ROW_NUMBER() OVER (ORDER BY amt_spent) AS num, name, amt_spent
FROM spent
)
SELECT mv.name, ms.name
FROM most_visited mv INNER JOIN most_spent ms
ON mv.num = ms.num
ORDER BY mv.num
Just join table1 and table2 with name as key like bellow:
select a.name,
b.name,
a.NumOfVisitField,
b.TotalSpentField
from table1 a
left join table2 b on a.name = b.name