Fetching fields with specific criteria - Oracle - sql

Question

I am trying to extract particular data from 2 tables based on specific criteria. But the result is not as expected. Can someone please help?
Criteria:
Need to fetch id pairs whose type is A alone.
Tables:
Table A
ID1 ID2
579643307310619501 644543316683180704
296151129721950503 328945291791563504
Table B
ID TYPE
579643307310619501 A
579643307310619501 B
579643307310619501 C
644543316683180704 A
296151129721950503 A
328945291791563504 A
Expected Result:
ID1 ID2
296151129721950503 328945291791563504
(Since only this pair is of type A alone, individually)
Note: The IDs, ID1 and ID2 both must be present in ID field of Table B.
What I've tried:
SELECT id1, id2
FROM A
JOIN B ON A.id1 = B.id
WHERE A.id1 IN (SELECT id FROM B)
AND A.id2 IN (SELECT id FROM B)
AND B.type='A'
GROUP BY id1, id2
HAVING count(*)=1;

Answer 1

In the approach below, I use a CTE to first identify all ID values having exclusively the 'A' type. Then I join TableA to this CTE, twice, to filter off any records either of whose ID1 or ID2 values are not in the exclusively 'A' type list.
WITH cte (ID) AS (
SELECT ID
FROM TableB
GROUP BY ID
HAVING SUM(CASE WHEN TYPE <> 'A' THEN 1 ELSE 0 END) = 0
)
SELECT a.ID1, a.ID2
FROM TableA a
INNER JOIN cte t1
ON a.ID1 = t1.ID
INNER JOIN cte t2
ON a.ID2 = t2.ID;
Find below a working demo (for SQL Server - I can't get Oracle to work anywhere).
Demo

Answer 2

Here is an Oracle solution using the MINUS operator.
The top sub-query gets the set of records where both ID1 and ID2 are of type 'A'. The bottom sub-query gets the set of records where either ID1 or ID2 is not of type 'A'. The result is the set of records in the top set which are not also in the bottom set.
select a.id1, a.id2
from a
join b b1 on b1.id = a.id1
join b b2 on b2.id = a.id2
where b1.type = 'A'
and b2.type = 'A'
minus
select a.id1, a.id2
from a
join b b1 on b1.id = a.id1
join b b2 on b2.id = a.id2
where b1.type != 'A'
or b2.type != 'A'
/
This SQL Fiddle demo returns the right row but there's a bit of a problem with its display: for some reason the numbers are rounded down.
Note on performance
This hits table A twice and table B four times. With small tables and a well-sized buffer cache this is not so important.
#TimBiegeleisen uses the WITH clause and that approach only hits each table once. However, Oracle will materialize the CTE as a temporary table. The overhead of doing this for such small amounts of data makes his solution consistently slower than mine. Including an /*+ inline */ hint in the CTE projection prevents Oracle from materializing the temporary table and the performance of the two queries becomes comparable.
However, if the tables become large enough there will be a point at which the WITH clause approach with a materialized temporary table is the more performative approach. As always with query tuning, the specifics matter greatly and benchmarking is the key to success.

Answer 3

Here is a sample for Oracle and my solution.
This is valid for any letter, A, B, C... If you want only for A, add an additional filter in the where of the main query.
create table a (id1 number,id2 number, constraint pk_a primary key(id1,id2));
create table b (id number, type char(1), constraint pk_b primary key(id,type));
insert into a values(57,64);
insert into a values(29,32);
insert into b values(57,'A');
insert into b values(57,'B');
insert into b values(57,'C');
insert into b values(64,'A');
insert into b values(29,'A');
insert into b values(32,'A');
commit;
select a.*
from a, b b1, b b2
where a.id1 = b1.id
and a.id2 = b2.id
and b1.type = b2.type
and not exists (select null
from b b1bis
where b1bis.id = b1.id
and b1.type <> b1bis.type)
and not exists (select null
from b b2bis
where b2bis.id = b2.id
and b2.type <> b2bis.type);