Count on UNION in Oracle - sql

Question

I have 3 table and I need to get the details from 2 tables where the count of UNION is greater than 1.But need to apply certain conditions as well
Table A
id entity_id name category
1 45 abcd win_1
2 46 efgh win_2
3 47 efgh1 win_2
4 48 dfgh win_5
5 49 adfgh win_4
Table B
id product_id name parent_id
1 P123 asdf win_1
2 P234 adfgh win_4
Table 3 category_list
id cat_id name
1 win_1 Households
2 win_2 Outdoors
3 win_3 Mixed
4 win_4 Omni
Now I need to have the count of UNION from Table A and Table B where they have count of cat_id greater than 1 and Table A.name != Table B.name
The result which I require is
p_id name cat_id
45 abcd win_1
P123 asdf win_1
46 efgh win_2
47 efgh1 win_2
win_5 is excluded as the count is one and win_4 should be excluded as name in Table A nd B is same.
I have run out of Ideas as i am relatively new to Oracle and DB.Any help is appreciated.

Answer 1

I think you can use exists to ensure that the cat_id is present in both tables
select entity_id as p_id, name, category as cat_id
from table_a a
where exists (select null from table_b where a.category = table_b.parent_id)
union
select entity_id, name, parent_id
from table_b b
where exists (select null from table_a where b.parent_id = table_a.category)

Answer 2

I believe you are looking for something like this -
Select T2.*
from
(Select category
from
(Select name, category from TableA
Union all
Select name, parent_id as category from TableB) t
group by category
having count(distinct name) > 1) T1
Join
(Select entity_id as Pid, name, category from TableA
Union
Select product_id as Pid, name, parent_id as category from TableB) T2
ON T1.category = T2.category;

Answer 3

Would you try this code.
First CTE (Common Table Expression) "list_union" gets the records for each table those have different names then makes the union. with the second CTE "list_cnt" counts the categories and finally gets the result cnt>1 with the last select statement as you pictured.
With
list_union AS (
SELECT
id,
----------
TO_CHAR(entity_id) entity_id,
----------
name,
category
FROM table_A a
WHERE NOT EXISTS(SELECT 1 FROM table_B b WHERE a.name=b.name)
----------
UNION ALL
----------
SELECT
id,
product_id,
name,
parent_id
FROM table_B b
WHERE NOT EXISTS(SELECT 1 FROM table_A a WHERE a.name=b.name)
)
,list_cnt AS (
SELECT
l.*,
----------
COUNT(*) over (PARTITION BY category) cnt
----------
FROM list_union l
)
SELECT
entity_id AS p_id,
name,
category AS cat_id
FROM list_cnt
WHERE cnt>1
ORDER BY cat_id ASC, p_id ASC
;

Answer 4

Just use a union all and window functions:
select ab.*
from (select ab.*,
count(distinct name) over (partition by category) as cnt
from ((select a.* from a
) union all
(select b.* from b
)
) ab
) ab
where cnt > 1;
Although you describe the problem as:
Now I need to have the count of UNION from Table A and Table B where they have count of cat_id greater than 1 and Table A.name != Table B.name
You seem to just want cat_ids that have different names across the two tables. Your sample data includes cat_id = 'win_2', which is not even in the second table.