I have to come up with 5 different ways (unique execution plans) to process the following query.
Find the items that are delivered by all suppliers.
My database holds the following tables:
QSPL – it holds a list of supplier names
SPLNO (number)
SPLNAME (varchar)
QDEL– it holds delivery items, suppliers, and departments
DELNO (number)
DELQTY (number)
ITEMNAME (varchar)
DEPTNAME (varchar)
SPLNO (number)
QITEM – it holds list of items
ITEMNAME (varchar)
ITEMTYPE (varchar)
ITEMCOLOR (varchar)
I was able to successfully come up with the following four unique queries.
1.
select itemname --, etc.
from qitem
where itemname not in
(select itemname
from qitem, qspl
where (char(splno)+itemname) not in
(select char(splno)+itemname
from qdel));
2.
select itemname --,etc.
from qitem
where not exists
(select *
from qspl
where not exists
(select *
from qdel
where qdel.itemname = qitem.itemname
and Qdel.splno = qspl.splno));
3.
select a.itemname --, etc
from qitem a join qdel b on a.itemname = b.itemname
group by a.itemname
having count (distinct splno) = (select count(*) from qspl);
4.
select itemname
from qdel
group by itemname
having count (distinct splno) = (select count(*) from qspl);
I have no idea what to do for a 5th unique query.
Does anyone have a clue?
I tried to put this question in the best possible context with significant detail, feedback is greatly appreciated.
Thanks
Maybe some SQL 86 syntax:
select a.itemname --, etc
from qitem a, qdel b
where a.itemname = b.itemname
group by a.itemname
having count (distinct splno) = (select count(*) from qspl);
Or an outer join
select a.itemname --, etc
from qspl s, qdel b
WHERE s.splno (+)= b.splno
group by s.splno
having count (distinct b.splno) = (select count(*) from qspl);
This is another unique way (which I'm sure it's horribly inefficient):
select distinct splname
from (
select qi.itemname,
qs.splname,
count(distinct qi.itemname) over () as total_items,
count(distinct qd.itemname) over (partition by qd.splno) as items_per_supp
from qitem qi
left join qdel qd on qi.itemname = qd.itemname
left join qspl qs on qs.splno = qd.splno
) t
where total_items = items_per_supp
Or a variant of your #3 which will probably use a different execution plan:
with supplier_items as (
select splno, count(*) item_count
from qdel
group by splno
)
select splname
from qspl qs
join supplier_items si on qs.splno = si.splno
where si.item_count = (select count(*) from qitem);
Since this is homework, I will be obtuse: Check out the Oracle MINUS operator.
Related
I have 3 tables:
companies (id, name)
union_products (id, name)
products (id, company_id, union_product_id, price_per_one_product)
I need to get all companies which have products with union_product_id in (1,2) and total price of products (per company) is less than 100.
What I am trying to do now:
select * from "companies" where exists
(
select id from "products"
where "companies"."id" = "products"."company_id"
and "union_product_id" in (1, 2)
group by id
having COUNT(distinct union_product_id) = 2 AND SUM(price_per_one_product) < 100
)
The problem I stuck with is that I'm getting 0 rows from the query above, but it works if I'll change COUNT(distinct union_product_id) = 2 to 1.
DB fiddle: https://www.db-fiddle.com/f/iRjfzJe2MTmnwEcDXuJoxn/0
Try to join the three tables as the following:
SELECT C.id, C.name FROM
products P JOIN union_products U
ON P.union_product_id=U.id
JOIN companies C
ON P.company_id=C.id
WHERE P.union_product_id IN (1, 2)
GROUP BY C.id, C.name
HAVING COUNT(DISTINCT P.union_product_id) = 2 AND
SUM(P.price_for_one_product) < 100
ORDER BY C.id
See a demo.
SELECT c.name FROM "companies" c
JOIN "products" p ON c.id = p.company_id
WHERE union_product_id IN (1, 2) AND price_for_one_product < 100
GROUP BY c.name
HAVING COUNT(DISTINCT p.name) =2
This would provide you all the company(s) name(s) which has provides both union_product_id 1 and 2 and the price_for_one_product/ price_per_one_product is less than 100.
Note: You might need to change price_for_one_product with price_per_one_product, as in question you have used price_per_one_product but db-fiddle link table defination has used price_for_one_product.
I'm a beginner of the oracle, currently, I'm doing a question using subquery(without JOIN) and normal (with JOIN) query, but at the end, the results are different from this two query,
I can't figure out this problem, does anyone know?
The question is asking about list the dog owner details which has booked at least twice in this platform
SELECT PET_OWNER.Owner_id,Oname,OAdd,COUNT(*) AS BOOKING
FROM PET_OWNER
WHERE Owner_id IN(
SELECT Owner_id
FROM PET
WHERE PType = 'DOG' AND Pet_id IN(SELECT Pet_id FROM BOOKING))
GROUP BY PET_OWNER.Owner_id,Oname,OAdd
HAVING COUNT(*) >=2
ORDER BY PET_OWNER.Owner_id;
This subquery shows no rows selected,
SELECT PET_OWNER.Owner_id,Oname,OAdd,COUNT(*) AS BOOKING
FROM PET_OWNER,PET,BOOKING
WHERE PET_OWNER.Owner_id = PET.Owner_id AND
PET.Pet_id = BOOKING.Pet_id AND
PType = 'DOG'
GROUP BY PET_OWNER.Owner_id,Oname,OAdd
HAVING COUNT(*) >=2
ORDER BY PET_OWNER.Owner_id;
this query shows 10 records which are the correct answer for this question
I expected these two queries come out with the same result but it is not
does anyone know what is wrong with it?
can anyone show me how to convert this code to subquery?
Because duplicated join key will cause duplicatation in result.
In your case, the Owner_id should be non-unique in the PET table.
It is still possible to get the correct answer by using join. And as the owner_id in the subquery t is unique, so the execution plan should be same with the subquery version.
select p.* from Pet_Owner p
join (
select PET.Owner_id
from PET
inner join Booking on Booking.Pet_id = PET.Pet_id
where pType = 'DOG'
group by PET.Owner_id
having count(1) >= 2) t
on t.Owner_id = p.Owner_id
order by p.Owner_id
By the way, your SQL code is so old-school as it is in ANSI-89, while the join syntax is already in ANSI-92. I know many school teachers still love the old style, I hope you can read both, but only write code in ANSI-92 way.
What happen is that it will give you distinct values on your PET_OWNER.Owner_id,Oname,OAdd. So what we need is to group by owner_id first.
Here's your query. get first those owner_id with count() >= 2 as subquery
select * from Pet_Owner where Owner_id in (
select t1.Owner_id from PET_OWNER t1
inner join PET t2 on t1.Owner_id = t2.Owner_id
inner join Booking t3 on t3.Pet_id = t2.Pet_id
where pType = 'DOG'
group by t1.Owner_id
having count(1) >= 2)
order by Owner_id
not using join, nested subqueries is our only option
select * from Pet_Owner where Owner_id in (
select owner_id from Pet_Owner where Owner_id in
(select Owner_id from Pet where Pet_id in
(select Pet_id in Booking) and PType='DOG')
group by owner_id
having count(1) >= 2)
order by Owner_id
if you are trying to the # of dogs per owner:
select * from Pet_Owner where Owner_id in (
select Owner_id from Pet where Pet_id in
(select Pet_id in Booking) and PType='DOG'
group by owner_id
having count(1) >= 2)
) order by Owner_id
I have 3 table as follow :
s(s# int,sname nchar(10))
p(p# int,pname nchar(10))
sp(s# int,p# int)
table "s" is table of suppliers and "s#" is primary key of it.also table "p" is table of products and "p#" is primary key on it."s#" and "p#" are foreign key in table "sp".
now my question is "How can I select name of suppliers from table "s" which producing all of products in table "p"...
SELECT p.*, s.sname FROM s, sp, p WHERE s.s# = sp.s# AND sp.p# = p.p#;
This statement will output all products with all their suppliers.
Now we group my suppliers, and count how many products they provide:
SELECT s.sname, count(*) FROM s, sp, p WHERE s.s# = sp.s# AND sp.p# = p.p# GROUP BY s.s#;
Now we know exacly, how many products each supplier provides. And we also know, how many products are in the productstable:
SELECT count(*) FROM p;
If you compare these values, you get your desired result:
SELECT amounts.name FROM
( SELECT s.sname AS name, count(*) AS offers
FROM s, sp, p
WHERE s.s# = sp.s# AND sp.p# = p.p#
GROUP BY s.s# ) amounts, -- this is a temp. tablename
( SELECT count(*) AS avaiable FROM p ) countTbl
WHERE amounts.offers = countTbl.avaiable;
Notice, that I didn't test the query. But you should get an idea on how to solve this problem.
It might also be possible to write this query more efficient, but this one can be understood easily.
There are two ways to do this, the first I thought of was to invert the logic.
Rather than attempting to find every entry of P let's just look for any that don't exist, then exclude those entries from S:
SELECT *
FROM S
WHERE
NOT EXISTS (
SELECT *
FROM P
LEFT JOIN SP
ON P.P# = SP.P#
AND SP.S# = S.S#
WHERE
SP.P# IS NULL
)
I have 4 tables with the following structure:
Table artist:
artistID lastname firstname nationality dateofbirth datedcease
Table work:
workId title copy medium description artist ID
Table Trans:
TransactionID Date Acquired Acquistionprice datesold askingprice salesprice customerID workID
Table Customer:
customerID lastname Firstname street city state zippostalcode country areacode phonenumber email
First question is which artist has the most works of artsold and how many of the artist works have been sold.
My SQL query is this:
SELECT * From dtoohey.artist A1
INNER JOIN
(
SELECT COUNT(W1.ArtistID) AS COUNTER, artistID FROM dtoohey.trans T1
INNER JOIN dtoohey.work W1
ON W1.workid = T1.Workid
GROUP BY W1.artistID
) TEMP1
ON TEMP1.artistID = A1.artistID
WHERE A1.artistID = TEMP1.artistId
ORDER BY COUNTER desc;
I am to get the whole table but I only want show only the first row which is the highest count how do I do that??
I have tried inserting WHERE ROWNUM <=1 but it shows artist ID with 1
qns 2 is sales of which artist's work have resulted in the highest average profit (i.e) the average of the profits made on each sale of worksby an artist), and what is that amount.
My SQL query is:
SELECT A1.artistid, A1.firstname FROM
(
SELECT
(salesPrice - AcquisitionPrice) as profit,
w1.artistid as ArtistID
FROM dtoohey.trans T1
INNER JOIN dtoohey.WORK W1
on W1.workid = T1.workid
) TEMP1
INNER JOIN dtoohey.artist A1
ON A1.artistID = TEMP1.artistID
GROUP BY A1.artistid
HAVING MAX(PROFIT) = AVG(PROFIT);
I'm not able to execute it
I have tried query below but still not able to get it keep getting the error missing right parenthesis
SELECT A1.artistid, A1.firstname, TEMP1.avgProfit
FROM
(
SELECT
AVG(salesPrice - AcquisitionPrice) as avgProfit,
W1.artistid as artistid
FROM dtoohey.trans T1
INNER JOIN dtoohey.WORK W1
ON W1.workid = T1.workid
GROUP BY artistid
ORDER BY avgProfit DESC
LIMIT 1
) TEMP1
INNER JOIN dtoohey.artist A1
ON A1.artisid = TEMP1.artistid
Sometimes ORA-00907: missing right parenthesis means exactly that: we have a left bracket without a matching right one. But it can also be thrown by a syntax error in a part of a statement bounded by parentheses.
It's that second cause here: LIMIT is a Mysql command which Oracle does not recognise. You can use an analytic function here:
SELECT A1.artistid, A1.firstname, TEMP1.avgProfit
FROM
(
select artistid
, avgProfit
, rank() over (order by avgProfit desc) as rnk
from (
SELECT
AVG(salesPrice - AcquisitionPrice) as avgProfit,
W1.artistid as artistid
FROM dtoohey.trans T1
INNER JOIN dtoohey.WORK W1
ON W1.workid = T1.workid
GROUP BY artistid
)
) TEMP1
INNER JOIN dtoohey.artist A1
ON A1.artisid = TEMP1.artistid
where TEMP1.rnk = 1
This uses the RANK() function which will return more than one row if several artists achieve the same average profit. You might want to use ROW_NUMBER() instead. Analytic functions can be very powerful. Find out more.
You can apply ROWN_NUMBER(), RANK() and DENSE_RANK() to any top-n problem. You can use one of them to solve your first problem too.
"however the avg profit is null."
That's probably a data issue. If one of the numbers in (salesPrice - AcquisitionPrice) is null the result will be null, and won't be included in the average. If all the rows for an artist are null the AVG() will be null.
As it happens the sort order will put NULL last. But as the PARTITION BY clause sorts by AvgProfit desc that puts the NULL results at rank 1. The solution is to use the NULLS LAST in the windowing clause:
, rank() over (order by avgProfit desc nulls last) as rnk
This will guarantee you a non-null result at the top (providing at least one of your artists has values in both columns).
1st question - Oracle does not guarantee the order by which rows are retrieved. Hence you must first order and then limit the ordered set.
SELECT * from (
SELECT A1.* From dtoohey.artist A1
INNER JOIN
(
SELECT COUNT(W1.ArtistID) AS COUNTER, artistID FROM dtoohey.trans T1
INNER JOIN dtoohey.work W1
ON W1.workid = T1.Workid
GROUP BY W1.artistID
) TEMP1
ON TEMP1.artistID = A1.artistID
WHERE A1.artistID = TEMP1.artistId
ORDER BY COUNTER desc
) WHERE ROWNUM = 1
2nd question: I believe (haven't tested) that you have that LIMIT 1 wrong. That keyword is for use with Bulk collecting.
I have a table of 3 columns:
AuthorID (id can be repeated)
JournalName (name can be repeated)
AuthorScore
I need a query that gets JournalName and the count of all authors having their maximum score in this journal.
Thank you in advance.
select
maxscorejournalinstances.journalname,
COUNT(*) as maxscorecount
from
(
select
journalname
from
foo inner join
(
select
authorid,
MAX(authorscore) as maxscore
from
foo
group by
authorid
) maxauthorscores
on foo.AuthorId = maxauthorscores.AuthorId
and foo.AuthorScore = maxauthorscores.maxscore
) maxscorejournalinstances
group by
maxscorejournalinstances.JournalName
Note that if an author has the same high score in two or more journals, each of those journals will be included in the resultset.
SELECT AuthorID, MAX(AuthorScore) as AuthorScore,
(
SELECT JournalName
FROM tab t2
WHERE t1.AuthorID = t2.AuthorID AND t2.AuthorScore = MAX(t1.AuthorScore)
) as JournalName
FROM tab t1
GROUP BY AuthorID
select
x.journalname, count(x.authorid)
from tableX x
inner join
(
select authorid, max(authorscore) max_authorscore
from tableX
group by authorid
) tmp on x.authorid=tmp.authorid and x.authorscore=tmp.max_authorscore
group by journalname
Something like this may work.
select authorid, journalname, authorscore, max(authorscore) over(parition by authorid)
from <table>
order by journalname
Doing some research on sql olap function should point you in the right direction if this doesn't work.
Sounds like you need 2 queries as the data returned can not be returned in one record set where the data layout is simple to see.
The count of authors per journal,
select JournalName, count(distinct AuthorID)
from table
group by JournalName
The author's max score per journal,
select JournalName, AuthorID, max(AuthorScore)
from table
group by JournalName, AuthorID