How to do a select statement to claim relationship exist? [closed] - php

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External subject group
| pk | group_id | subid |
|----|----------|-------|
| 1 | 1 | s1 |
| 2 | 1 | s2 |
| 3 | 1 | s3 |
| 4 | 2 | x1 |
| 5 | 2 | x2 |
| 6 | 3 | y1 |
| 7 | 3 | y2 |
| 8 | 3 | y3 |
Internal subject group
| pk | group_id | subid |
|----|----------|-------|
| 1 | 1 | a1 |
| 2 | 1 | a2 |
| 3 | 1 | a3 |
| 4 | 2 | b1 |
| 5 | 3 | c1 |
| 5 | 3 | c2 |
| 7 | 3 | c3 |
| 8 | 3 | b4 |
I am using php and sql (oracle) at the moment. For example,
I have array of external subjects:
[s1, s2, s3]
I have array of internal subjects
[a1, a2, a3]
My attempt is that (incorrectly)
SELECT
group_id
FROM
external_subject_group e_s_g,
internal_subject_group i_s_g
WHERE
e_s_g.group_id = i_s_g.group_id AND
e_s_g.subid = "s1" AND
e_s_g.subid = "s2" AND
e_s_g.subid = "s3" AND
i_s_g.subid = "a1" AND
i_s_g.subid = "b1" AND
i_s_g.subid = "c1"
The group id either exist or empty.
Basically, I try to wrap this sql query into a php function. If the query returns the relationship id. I know the relationship [s1, s2, s3] x [a1, a2, a3] exist.
for example, another relationship is [x1, x2] x [b1].

Answer 1

I suspect you want more than just a simple where condition, and that you are looking for a way to identify a group that has all 3 values. Here are a couple of alternative queries. The first is my best guess, the second is just for comparison and you can trial these examples at SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE Table1
(PK int, GROUP_ID int, SUBID varchar2(20))
;
INSERT ALL
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (1, 1, 's1')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (2, 1, 's2')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (3, 1, 's3')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (4, 2, 'x1')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (5, 2, 'x2')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (6, 3, 'y1')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (7, 3, 'y2')
INTO Table1 (PK, GROUP_ID, SUBID)
VALUES (8, 3, 'y3')
SELECT * FROM dual
;
The following query uses GROUP BY and HAVING SUM(...) as a constct to require that ALL 3 wanted subid's MUST be used.
Query 1:
select group_id
from Table1
group by group_id
having SUM(case when subid in('s1','s2','s3') then 1 else 0 end) = 3
Result:
| GROUP_ID |
|----------|
| 1 |
Query 2:
This query only requires that ANY ONE of the subids listed have been used.
select distinct group_id
from Table1
where subid in('s1','s2','s3')
Result:
| GROUP_ID |
|----------|
| 1 |
+EDIT
You might also need to use UNION ALL
select group_id
from (
select pk,group_id,subid from external_subject_group e_s_g
UNION ALL
select pk,group_id,subid from internal_subject_group i_s_g
) t1
group by group_id
having SUM(case when subid in('s1','s2','s3','a1','a2','a3') then 1 else 0 end) = 6