How can I select the ID of a row with the max value of another column in a query that joins multiple tables?
For example, say I have three tables. tblAccount which stores a grouping of users, like a family. tblUser which stores the users, each tied to a record from tblAccount. And each user can be part of a plan, stored in tblPlans. Each plan has a Rank column that determines it's sorting when comparing the levels of plans. For example, Lite is lower than Premium. So the idea is that each user can have a separate plan, like Premium, Basic, Lite etc..., but the parent account does not have a plan.
How can I determine the highest plan in the account with a single query?
tblAccount
PKID
Name
1
Adams Family
2
Cool Family
tblUsers
PKID
Name
AccountID
PlanID
1
Bob
1
3
2
Phil
2
2
3
Suzie
2
1
tblPlans
PKID
Name
Rank
1
Premium
3
2
Basic
2
3
Elite
4
4
Lite
1
Here's the result I'm hoping to produce:
AccountID
Name
HighestPlanID
PlanName
2
Adams Family
1
Premium
I've tried:
SELECT U.AccountID, A.Name, MAX(P.Rank) AS Rank, P.PKID as HighestPlanID, P.Name as PlanName
FROM tblPlans P
INNER JOIN tblUsers U ON U.PlanID = P.PKID
INNER JOIN tblAccounts A ON U.AccountID = A.PKID
WHERE U.AccountID = 2
and the query will not always work, selecting the MAX of Rank does not select entire row's values from tblPlans.
I am looking for a solution that is compatible with mysql-5.6.10
You can join the tables and use ROW_NUMBER() to identify the row you want. Then filtering is ieasy.
For example:
select *
from (
select a.*, p.*,
row_number() over(partition by a.pkid order by p.rank desc) as rn
from tblaccount a
join tblusers u on u.accountid = a.pkid
join tblplans p on p.pkid = u.planid
) x
where rn = 1
Inside the subquery you can add where u.accountid = 2 to retrieve a single account of interest, instead of all of them.
With the help of #the-impaler, I massaged their answer a bit and came out with something very similar:
select *
from (
select a.*, p.*
from tblaccount a
join tblusers u on u.accountid = a.pkid
join tblplans p on p.pkid = u.planid
where u.accountid = 2
order by p.rank desc
) x limit 1
The subquery sorts each user by plan rank from top to bottom, and then the top level query selects the top most row with limit 1. It seems to work!
Related
In a MySQL 5.7 database, I have the following User table:
Name
Id
David
1
Frank
2
And the following Order table:
Id
Price
UserId
1
55
1
2
68
1
3
50
1
4
10
2
For every user, I want to select the price of the order with the biggest ID.
I can use the following query which adds additional complexity due to the nested subquery :
SELECT
User.Name,
last_user_order.Price
FROM User
LEFT JOIN (
SELECT Price, UserId FROM Order
ORDER BY Id DESC LIMIT 1
) AS last_user_order ON last_user_order.UserId = User.Id
There exist many questions here where the column to be selected is the same than the one being ordered. Hence, it is possible to use MAX in the first SELECT statement to avoid a subquery. Is it possible to avoid a subquery in my case?
For every user, I want to select the price of the order with the biggest ID.
That looks like:
SELECT
u.*,
o.Price,
FROM
User u
INNER JOIN Order o ON u.ID = o.UserID
INNER JOIN
(
SELECT MAX(ID) as OrderID FROM Order GROUP BY UserId
) maxO ON o.Id = maxO.OrderId
SELECT User.Name,
( SELECT Order.Price
FROM Order
WHERE Order.UserId = User.Id
ORDER BY Order.Id DESC LIMIT 1 ) LastPrice
FROM User;
I am using MySQL 5.6.
I have a SQL table with a list of users:
id name
1 Alice
2 Bob
3 John
and a SQL table with the list of gifts for each user (numbered in order of preference):
id gift rank
1 balloon 2
1 shoes 1
1 seeds 3
1 video-game 1
2 computer 2
3 shoes 2
3 hat 1
And I would like a list of the preferred gift for each user (the highest rank - if two gifts have the same rank, pick only one randomly) (bonus: if the list could be randomized, that would be perfect!):
id name gift rank
2 Bob computer 2
1 Alice shoes 1
3 John hat 1
I tried to use the clause GROUP BY but without any success.
Considering rank as a part of your data; Without using window functions or complex sub queries
SELECT u.id, u.name, g.gift
FROM users u
JOIN gifts g ON g.id = u.id
LEFT JOIN gifts g2 ON g2.id = g.id AND g2.rank > g.rank
WHERE g2.id IS NULL;
Added link http://sqlfiddle.com/#!9/62f59e/15/0
You can use row_number to get one row for each User.(Mysql 8.0+)
SELECT A.ID,NAME,GIFT,`RANK` FROM USERS A
LEFT JOIN (
SELECT ID,GIFT,`RANK` FROM
(SELECT *,ROW_NUMBER() OVER(PARTITION BY ID ORDER BY `RANK` ASC) AS RN FROM X) X
WHERE RN =1
) B
ON A.ID= B.ID
I do not know DB what you use. And I'm not an expert in SQL(I can have some mistake in next). But I think it is not difficult.
So I can give you just advice that you have to think gradually. Let me write.
First All I need is the highest rank. So I have to get this.
SELECT MAX(RANK)
FROM GIFT
GROUP BY ID
And then I think that I need get gifts from this rank.
SELECT GIFT.*
FROM GIFT
INNER JOIN(
SELECT ID, MAX(RANK)
FROM GIFT
GROUP BY ID
) filter ON GIFT.ID = filter.ID AND GIFT.RANK = filter.RANK
I think this is the table what you want!
So If below code works, That's what you really want.
SELECT *
FROM USER
LEFT OUTER JOIN(
above table
) GIFT ON USER.ID = GIFT.ID
But Remember this, I said I'm not an expert in SQL. There can be better way.
Checkout the query
SELECT tbluser.id,name,gift,rank into tblrslt
FROM tbluser
LEFT JOIN tblgifts
ON tbluser.id = tblgifts.id order by id,rank;
SELECT tt.*
FROM tblrslt tt
INNER JOIN
(SELECT id, min(rank) AS rank
FROM tblrslt
GROUP BY id) groupedtt
ON tt.id = groupedtt.id
AND tt.rank = groupedtt.rank order by id
In MySQL versions older than 8 you have no ranking functions available. You'll select the minimum rank per user instead and use these ranks to select the gift rows. This means you access the gifts table twice.
I suggest this:
select *
fron users u
join gifts g
on g.id = u.id
and (g.id, g.rank) in (select id, min(rank) from gifts group by id)
order by u.id;
If you also want to show users without gifts, simply change the inner join to a left outer join.
I have a couple tables in MySQL DB
EID Name
1 Title A
2 Title B
3 Title C
LID EID Location Address Order
1 1 Office NY 1
2 1 Home IL 2
3 2 Office CA 1
4 3 Home NJ 2
I have the above 2 tables (Employee and Location). I would like to know the location of each Employee with office as a preferred choice and if 'office' does not exist then would need 'Home' location . The order column defined the order/priority of what is needed.
here is the output needed
EID LID Name Location Address
1 1 Title A Office NY
2 3 Title B Office CA
3 4 Title C Home NJ
The first join of the query below just connects the Employee and Location tables, but note that it results in all records from Location being joined. The critical part of the below query is the second INNER JOIN to a subquery. This subquery identifies the minimum (i.e. highest priority) order for each employee ID. This is then used to discard records from the first join which are not the highest priority.
SELECT t1.EID,
t2.LID,
t1.Name,
t2.Location,
t2.Address
FROM Employee t1
INNER JOIN Location t2
ON t1.EID = t2.EID
INNER JOIN
(
SELECT EID, MIN(`Order`) AS min_order
FROM Location
GROUP BY EID
) t3
ON t2.EID = t3.EID AND
t2.Order = t3.min_order
One other note: Don't name your columns Order, which is a MySQL keyword. To get my query to work, I had to put it in backticks, which is inconvenient to say the least, and possibly error prone.
Demo here:
SQLFiddle
There are two posibility to get your result.
1)If you need Based on Order result then use this query
SELECT e1.EID, l1.LID, e1.Name, l1.Location, l1.Address
FROM Employee e1
JOIN
(SELECT MIN(`Order `) as Minorder, EID, LID, Location, Address, Order
FROM Location l1
GROUP BY EID) l1
ON l1.EID = e1.EID AND l1.Minorder = l1.Order;
2)if you need result Based on EID then use this query
SELECT e1.EID,l1.LID,e1.Name,l1.Location,l1.Address
FROM Employee e1 JOIN
(SELECT MIN(`EID`)as Mineid,EID,LID,Location,Address,`Order` FROM Location l1 GROUP BY EID)l1
ON l1.Mineid = e1.EID;
Extra Note:-
Plese donot use mysql inbuilt keyword as Column name or Table name for more information read this link click here
You can the expected result by using inner join
Select a.eid,b.Lid,a.name,b.location,b.address from Table1 a innner join (select * from Tableb group by eid) b on
a.eid=b.eid;
you can try this code this will help you as i think
select E.EID,E.name,ad.LID,ad.LOCATION,ad.ADDRESS,ad.[order]
from #emp E inner join #address ad on E.EID = ad.EID
inner join (select EID, min([order]) [order]
from #address
group by EID) tt on ad.EID = tt.EIDand ad.[order] = tt.[order]
SELECT art.*,arg. FROM rd_articles AS art
LEFT JOIN rd_argument AS arg ON art.cat=arg.id WHERE art.enabled=1 ORDER BY art.id DESC
LIMIT 10
This is simple join query
Article table structure is
ID cat Description Date
1 1 Abc 08-01-2014
2 1 Aaa 10-01-2014
3 2 Abcv 11-01-2014
4 3 Aaa 12-01-2014
5 3 Aaa 14-01-2014
Arguments table is
ID Name
1 A
2 B
3 C
I want pick last updated(Date) one item from each cat.
How ?
This assumes that the enabled column is in rd_articles:
SELECT art.*, arg.*
FROM (
SELECT * FROM rd_articles
INNER JOIN (
SELECT cat, MAX(date) AS maxdate
FROM rd_articles
WHERE enabled = 1
GROUP BY cat
) md ON rd_articles.cat = md.cat AND rd_articles.date = md.maxdate
) art
LEFT JOIN rd_argument AS arg ON art.cat = arg.id
The innermost query gets the maximum date for each category, then joins it to the rd_articles table to get only those rd_articles rows that have the latest date for each article. That becomes the cat alias, which is then left-joined to the arguments table just like in your original query. You can add the LIMIT 10 at the end if needed; I wasn't sure what to do with that.
Note that if there's a tie for a category's latest date, you'll get more than one row for each category. If a tie could happen you'll need to break the tie somehow, for example by using the description or the ID. Let me know if that's the case and I'll update my answer.
SELECT ART.*, ARG.*
FROM ARTICLE AS ART
INNER JOIN RD_AGRUEMENT AS ARG
ON ARG.ID = ART.ID
WHERE (ID, DATE) IN
(SELECT ID, MAX(DATE) FROM ARTICLE GROUP BY ID)
I have this problem with SQL and I can't figure it out.
Imagine that I have 3 tables as follows
Names
Nameid name
1 Starbucks Coffee
2 Johns Restaurant
3 Davids Restaurant
user_likes
userid Nameid
1 1
2 1
2 3
user_visited
userid Nameid
1 2
I want to find the places with the most number of (likes+visited). I also want to select all places not just those who have been liked or visited
I do:
SELECT n.nameid, n.name , COUNT(f.nameid) AS freq
FROM names AS n
LEFT JOIN user_likes ON n.nameid=user_likes.nameid
LEFT JOIN user_visited ON n.nameid=user_visited.nameid
ORDER BY freq DESC
But it doesn't give me the total frequency. The problem is, if a place is both visited and liked, it is counted only once, while I want it to be counted twice.
Any suggestions?
I've made a quick test and although I prefer Serge's solution, this one seemed to perform faster as the amount of items to join will be less:
SELECT n.nameId, n.name, coalesce(sum(likesCount), 0) totalCount FROM NAMES n
LEFT JOIN (
SELECT nameId, count(*) likesCount FROM user_likes
GROUP BY nameId
UNION ALL
SELECT nameId, count(*) visitsCount FROM user_visited
GROUP BY nameId
) s ON n.nameId = s.nameId
GROUP BY n.nameId
ORDER BY totalCount DESC
I'm assuming the following indexes:
alter table names add index(nameid);
alter table user_likes add index(nameid);
alter table user_visited add index(nameid);
Probably the OP can compare the efficiency of both queries with actual data and provide feedback.
SELECT n.name, t.nameid, COUNT(t.nameid) AS freq
FROM Names n
JOIN (
SELECT nameid FROM user_likes
UNION ALL
SELECT nameid FROM user_visited
) t
ON n.nameid = t.nameid
GROUP BY t.nameid ORDER BY freq DESC
Mosty, your usage of coalesce() gave me an idea and I came up with this:
SELECT n.nameid, n.name ,
SUM((IFNULL(user_likes.userid,0)>0)+(IFNULL(user_visited.userid,0)>0) ) AS freq
FROM names AS n LEFT JOIN user_likes ON n.nameid=user_likes.nameid LEFT JOIN
user_visited ON n.nameid=user_visited.nameid ORDER BY freq DESC
Since my example here was a simplification of my problem (I have to join more than two tables to the main table) I'm reluctant to use SELECT inside SELECT, because I know it's not very efficient. Do you see any fundamental problem with my solution?