Finding all duplicate rows with the given conditions - sql

Question

I have a table called Fruit which has two columns (id,cost) and I want to select id and cost, and find all duplicate rows where the cost is the same but the id is different. How can I write this query?
I write this query
SELECT id,cost
From Fruit a
WHERE (SELECT COUNT(*)
FROM Fruit b
WHERE a.cost = b.cost
) > 1
This works but only give me the rows where the cost is the same but the id might be same as well, I only want results where the cost is the same but id is different

Answer 1

This is what you need:
SELECT DISTINCT F1.*
FROM Fruit F1
INNER JOIN Fruit F2 ON F1.id <> F2.id AND F1.cost = F2.cost
If you want repeated id-cost pairs to be listed too, just remove the DISTINCT.

Answer 2

You can add a simple condition where id are not equal.
SELECT id,cost From Fruit a WHERE (SELECT COUNT(*) FROM Fruit b WHERE a.cost = b.cost and a.id <> b.id ) > 1
Here <> is operator for not equal.
I hope it will help you :)

Answer 3

you could select all the rows with cost duplicated using a group by and having ccount(*) >1
and for this get all the row that match
select a.id, a.cost
from Fruit a
where cost in ( select b.cost
from fruit b
group by b.cost
having count(*) > 1
)
for avoid duplicated result you can add distinct
select distinct a.id, a.cost
from Fruit a
where cost in ( select b.cost
from fruit b
group by b.cost
having count(*) > 1
)

Answer 4

You can add a simple condition where id are not equal.
SELECT id,cost From Fruit a WHERE (SELECT COUNT(*) FROM Fruit b WHERE a.cost = b.cost and a.id <> b.id ) > 1
Here <> is the operator Of not equal in sql.

Answer 5

This works. Ran it in SQL Server because Oracle is broken on Fiddle, but should work on either system.
MS SQL Server 2014 Schema Setup:
CREATE TABLE ab
([id] int, [cost] int)
;
INSERT INTO ab
([id], [cost])
VALUES
(1, 5),
(2, 5),
(3, 15),
(3, 15),
(4, 24),
(5, 68),
(6, 13),
(7, 3)
;
Query 1:
with a1 as (
SELECT id
,cost
,rank () over (partition by cost order by id) dup
From ab
)
select * from a1 where dup > 1
Results:
| id | cost | dup |
|----|------|-----|
| 2 | 5 | 2 |
And then to return all values where there was a duplicate cost:
with a1 as (
SELECT id
,cost
,rank () over (partition by cost order by id) dup
From ab
)
,a2 as ( select * from a1 where dup > 1)
select * from ab
join a2 on ab.cost = a2.cost