Oracle PHP display only once - php

Question

There are two tables:
$inner_query =
"SELECT A.*, ROWNUM AS RN, TO_CHAR(A.last_newsletter_modify, 'DD/MM/YYYY') AS LAST_NEWSLETTER_MODIFY2
FROM ".$db_schema_name."newsletter_subscription A,
".$db_schema_name."newsletter_type B,
".$db_schema_name."newsletter_subtyp_profile C
WHERE A.id_subscription = C.id_subscription AND
C.id_type = B.id_type
ORDER BY e_mail";
If I run this query for id_subscription 734 it displays 3 times.
How can to display it just once?

Answer 1

Short answer: you are getting one row per newsletter_subtyp_profile. Subscription 734 is linked to three newsletter types, hence three rows of output.
You have three tables, not two, and the question would be clearer if you included full descriptions and sample data, and also got rid of the irrelevant PHP aspect and focussed on the SQL.
With some detective work, I make it this:
create table newsletter_subscription
( id_subscription integer primary key
, last_newsletter_modify date
, e_mail varchar2(50) not null );
create table newsletter_type
( id_type integer primary key
, description varchar2(40) not null unique );
create table newsletter_subtyp_profile
( id_subscription references newsletter_subscription
, id_type references newsletter_type
, constraint nsp_pk primary key (id_type,id_subscription) );
insert into newsletter_subscription values (600, date '2017-01-10', 'someone#somewhere.net');
insert into newsletter_subscription values (734, date '2017-02-05', 'someone#somewhereelse.net');
insert into newsletter_subscription values (800, date '2017-03-01', 'nobody#nowherewhere.net');
insert into newsletter_type values (1, 'Type One');
insert into newsletter_type values (2, 'Type Two');
insert into newsletter_type values (3, 'Type Three');
insert into newsletter_subtyp_profile values (734, 1);
insert into newsletter_subtyp_profile values (734, 2);
insert into newsletter_subtyp_profile values (734, 3);
Now run your query (I shortened the select list to simplify the output, and added b.description - a dummy column as I don't know what other columns you have on newsletter_type):
select a.id_subscription, a.e_mail
, to_char(a.last_newsletter_modify, 'DD/MM/YYYY') as last_newsletter_modify2
, b.description
from newsletter_subscription a,
newsletter_type b,
newsletter_subtyp_profile c
where a.id_subscription = c.id_subscription and
c.id_type = b.id_type
order by a.e_mail, c.id_type;
ID_SUBSCRIPTION E_MAIL LAST_NEWSLETTER_MODIFY2 DESCRIPTION
--------------- -------------------------- ----------------------- ---------------------
734 someone#somewhereelse.net 05/02/2017 Type One
734 someone#somewhereelse.net 05/02/2017 Type Two
734 someone#somewhereelse.net 05/02/2017 Type Three
btw the logic would be clearer if you used mnemonic aliases such as sub instead of a for newsletter_subscription, and also used standard ANSI joins and lost the uppercase:
select sub.id_subscription, sub.e_mail
, to_char(sub.last_newsletter_modify, 'DD/MM/YYYY') as last_newsletter_modify
, typ.description
from newsletter_subscription sub
join newsletter_subtyp_profile pro on pro.id_subscription = sub.id_subscription
join newsletter_type typ on typ.id_type = pro.id_type
where sub.id_subscription = 734
order by sub.e_mail, pro.id_type;

Answer 2

You can use window function row_number to get one row per id_subscription with max (or min id_type if you change the order by clause in the function to order by id_type):
$inner_query = "SELECT *
FROM (
SELECT A.*,
ROWNUM AS RN,
TO_CHAR(A.last_newsletter_modify, 'DD/MM/YYYY') AS LAST_NEWSLETTER_MODIFY2,
row_number() over (
partition by C.id_subscription
order by C.id_type desc nulls last
) as seqnum
FROM ".$db_schema_name."newsletter_subscription A
JOIN ".$db_schema_name."newsletter_subtyp_profile C
on A.id_subscription = C.id_subscription
JOIN ".$db_schema_name."newsletter_type B
on C.id_type = B.id_type
) t
WHERE seqnum = 1
ORDER BY e_mail";
Also notice that I have replace the old comma based join with widely recommended explicit JOIN syntax.