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.
Related
I have 3 tables
User Table
id
Name
1
Mike
2
Sam
Score Table
id
UserId
CourseId
Score
1
1
1
5
2
1
1
10
3
1
2
5
Course Table
id
Name
1
Course 1
2
Course 2
What I'm trying to return is rows for each user to display user id and user name along with the sum of the maximum score per course for that user
In the example tables the output I'd like to see is
Result
User_Id
User_Name
Total_Score
1
Mike
15
2
Sam
0
The SQL I've tried so far is:
select TOP(3) u.Id as User_Id, u.UserName as User_Name, SUM(maxScores) as Total_Score
from Users as u,
(select MAX(s.Score) as maxScores
from Scores as s
inner join Courses as c
on s.CourseId = c.Id
group by s.UserId, c.Id
) x
group by u.Id, u.UserName
I want to use a having clause to link the Users to Scores after the group by in the sub query but I get a exception saying:
The multi-part identifier "u.Id" could not be bound
It works if I hard code a user id in the having clause I want to add but it needs to be dynamic and I'm stuck on how to do this
What would be the correct way to structure the query?
You were close, you just needed to return s.UserId from the sub-query and correctly join the sub-query to your Users table (I've joined in reverse order to you because to me its more logical to start with the base data and then join on more details as required). Taking note of the scope of aliases i.e. aliases inside your sub-query are not available in your outer query.
select u.Id as [User_Id], u.UserName as [User_Name]
, sum(maxScore) as Total_Score
from (
select s.UserId, max(s.Score) as maxScore
from Scores as s
inner join Courses as c on s.CourseId = c.Id
group by s.UserId, c.Id
) as x
inner join Users as u on u.Id = x.UserId
group by u.Id, u.UserName;
I have 2 tables Journal and Users
Journal looks like this:
TransTime
RegNumber
UserID
5/26/2022 11:00:00
101
3
5/26/2022 11:30:00
102
2
5/26/2022 13:00:00
101
5
5/26/2022 14:30:00
103
4
5/26/2022 15:00:00
102
1
Users table
UserID
Name
1
Ross
2
Rachel
3
Chandler
4
Monica
5
Joey
What I would like to do is get a table of the Registers and their most recent user names. This should seem very simple. But since I am joining tables on the userID, I am getting all 5 records on the first table. But it should look like this:
RegNumber
LastUser
101
Joey
102
Ross
103
Monica
I have tried a variety of solutions but haven't found the right one. Any help is appreciated.
You can use a temptable or cte structure to rank your data based on RegNo and Trantime like below, then retrieve the most updated users for each journal:
CREATE TABLE #Journals (TranTime DATETIME, RegNo INT, UserId INT)
CREATE TABLE #Users (UserId INT, UserName NVARCHAR(100))
INSERT INTO #Users VALUES(1,'Ross'),(2,'Rachel'),(3,'Chandler'),(4,'Monica'),(5,'Joey')
INSERT INTO #Journals VALUES ('5/26/2022 11:00:00',101,3),('5/26/2022 11:30:00',102,2),
('5/26/2022 13:00:00',101,5),('5/26/2022 14:00:00',103,4),('5/26/2022 15:00:00',102,1)
;WITH cte as (
SELECT *,rn=ROW_NUMBER() OVER (PARTITION BY RegNo ORDER BY TranTime DESC)
FROM #Journals
)
SELECT RegNo, u.UserName
FROM cte
INNER JOIN #Users u ON u.UserId = cte.UserId
WHERE rn=1 --since sort by TranTime is descending, it'll give you the latest user for each specific RegNo
ORDER BY RegNo
Tested and it works on SQL Server 2016.
if you start with an inner join of the max transtime per regNumber, then join with user table:
Select J.RegNumber, U.Name
From Journal J
Inner join
(Select Max(TransTime) as TransTime, RegNumber
From Journal
Group by RegNumber) J2 on J.TransTime = J2.TransTime and J.RegNumber = J2.RegNumber
Inner join
Users U on J.UserID = U.UserID
Here is an option using a CTE:
;with cte as
(
Select RegNumber,
UserID = max(UserID)
From journal
group by RegNumber
)
Select RegNumber = C.RegNumber,
LastUser = U.Name
From cte C
Join users U ON U.Userid = C.UserID
order by C.RegNumber
This answer is not, at its core, substantively different from the others. However, in terms of being helpful to the target audience it's more readable, more self-documenting, and more standard in terms of formatting.
Sidebar: This SQL takes the data design at face value, as a given, with the implicit assumption that TransTime is the PK or at least uniquely indexed, possibly in conjunction with RegNumber. Bottom line, it would be good to have a little more info about the key structure along with the original question.
WITH LatestEntries AS
(
SELECT
MAX(TransTime) AS LatestTimeForReg
,RegNumber
FROM
Journal
GROUP BY
RegNumber
)
SELECT
J.RegNumber
,U.[Name] AS LastUser
FROM
LatestEntries LE
INNER JOIN Journal J ON LE.LatestTimeForReg = J.TransTime AND LE.RegNumber = J.RegNumber
INNER JOIN Users U ON J.UserID = U.UserID
ORDER BY
J.RegNumber
;
select u.Name, j.*
from journal j
inner join (
select max(TransTime) last_update, RegNumber
from journal
group by RegNumber
) t1
inner join j.RegNumber = t1.RegNumber
and t1.last_update = j.TransTime
left join Users_Journal uj on j.UserID= uj.UserID
I'm trying to find all users who have at least 1 transaction that has the StoreLocationID=123.
The basic query to get the count of users is:
SELECT COUNT(*)
FROM Users u
The transaction table looks like:
Transactions
- ID
- UserID
- Amount
- Date
- StoreLocationID
How can I find ALL users who have at least 1 transaction where StoreLocationID=123.
I can join on the table, but I just need to know if there is at least 1 row with StoreLocationID=123.
You can use a correlated subquery with an exists condition:
select *
from users u
where exists (
select 1
from transactions t
where t.userID = u.userID
and t.StoreLocationID = 123
)
This will give you all users that have at least one transaction on in store 123.
If you just want to count of such users, then:
select count(*)
from users u
where exists (
select 1
from transactions t
where t.userID = u.userID
and t.StoreLocationID = 123
)
Or:
select count(distinct userID) from transactions where StoreLocationID = 123
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 ;
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