SQL join not returning the correct data - sql

Question

Im trying to build some test cases in SQL. The problem is when im trying to join some table with a left join (wich if my understanding is correct should return both the matching and nonmatching row) when im trying to get the data with no matching ID, no data is returned. Here is the code :
select
E.ID_EVENEMENT,
t1.dateRecente as date_Star,
virage_c.no_contr,
t2.id as id_Univers,
t2.dateRecente as date_Univers,
t3.NUMERO_DOSSIER_STAR,
t3.dateRecente as Date_factcan,
t3.dateLimite,
t2.ID_PERSONNE_UNIVERS,
t1.ID_PERSONNE_STAR
FROM
STAR.EVENEMENT e
left join VIRAGE.CONTRAT virage_c
on e.NO_CONTRAT_OFFICIEL = to_char(virage_c.no_contr)
inner join
( SELECT
e.ID_EVENEMENT,
ep.ID_EVEN_INDIVIDU as ID_PERSONNE_STAR,
GREATEST( e.dt_creation,
NVL(e.DT_MODIF_STA_ELI, TO_DATE(1,'j')),
NVL(max(nt.dt_maj), TO_DATE(1,'j')),
NVL(max(ser.DT_CREATION), TO_DATE(1,'j')),
NVL(max(SER.DT_MAJ), TO_DATE(1,'j')),
NVL(max(aut.dt_transmis), TO_DATE(1,'j')),
NVL(max(AUT.DT_CREATION), TO_DATE(1,'j')) ) dateRecente
FROM
STAR.EVENEMENT e
left join STAR.Note nt
on e.ID_EVENEMENT = nt.ID_EVEN
left join STAR.SERVICE ser
on e.ID_EVENEMENT = ser.ID_EVEN
left join STAR.AUTORISATION aut
on ser.id_service = aut.id_service
left join STAR.DOCUMENT doc
on e.ID_EVENEMENT = doc.ID_EVENEMENT
left join STAR.ETAT ett
on e.ID_EVENEMENT = ett.ID_EVENEMENT
left join STAR.EVENEMENT_PARTICIPANT ep
on e.ID_EVENEMENT = ep.ID_EVENEMENT
GROUP BY
e.ID_EVENEMENT,
e.dt_creation,
e.DT_MODIF_STA_ELI,
ep.ID_EVEN_INDIVIDU ) t1
on t1.ID_EVENEMENT = E.ID_EVENEMENT
left JOIN
( SELECT
sf.STAREVENTNUMBER,
c.id,
par.ID as ID_PERSONNE_UNIVERS,
GREATEST( c.UPDATEDATE,
max(NVL(ca.UPDATEDATE, TO_DATE(1, 'J'))),
max(NVL(bo.UPDATEDATE, TO_DATE(1, 'J'))),
max(NVL(a.UPDATEDATE, TO_DATE(1, 'J'))),
max(NVL(p.UPDATEDATE, TO_DATE(1, 'J'))),
max(NVL(p.RELEASEDATE, TO_DATE(1, 'J'))),
max(NVL(p.PAYMENTDATE, TO_DATE(1, 'J'))) ) dateRecente
FROM
CV_CLAIMS_TRAVEL.STAR_FILE sf
join CV_CLAIMS_TRAVEL.CLAIM c
on sf.claimid = c.id
left join CV_CLAIMS_TRAVEL.BENEFIT_OPTION bo
on c.id = BO.CLAIMID
left join CV_CLAIMS_TRAVEL.ADJUDICATION a
on bo.id = a.BENEFITOPTIONID
left join CV_CLAIMS_TRAVEL.CLAIM_ACTIVITY ca
on c.id = CA.CLAIMID
left join CV_CLAIMS_TRAVEL.CLAIM_RELATIONSHIP cr
on c.id = CR.CLAIMID
left join CV_CLAIMS_TRAVEL.PAYEE pa
on cr.id = PA.CLAIMRELATIONSHIPID
left join CV_CLAIMS_TRAVEL.PAYMENT p
on pa.id = P.PAYEEID
left join CV_CLAIMS_TRAVEL.PARTY par
on par.ID = sf.PARTYID
WHERE
c.PRIMARYSTATUSLID in ('CLAIM_PRIMARY_STATUS:0000000003','CLAIM_PRIMARY_STATUS:0000000001')
OR ( c.PRIMARYSTATUSLID = 'CLAIM_PRIMARY_STATUS:0000000004'
AND bo.BENEFITOPTIONSTATUSLID in ('BENEFIT_OPTION_STATUS:0000000010',
'BENEFIT_OPTION_STATUS:0000000060',
'BENEFIT_OPTION_STATUS:0000000030')
)
group by
sf.STAREVENTNUMBER,
c.id,
c.UPDATEDATE,
par.ID ) t2
on e.ID_EVENEMENT = t2.STAREVENTNUMBER
LEFT JOIN
( SELECT DISTINCT
fact.NUMERO_DOSSIER_STAR,
GREATEST( to_date(fact.VSTDTCHG,'yyyymmdd'),
to_date(fact.VSTDICHK,'yyyymmdd'),
to_date(decode(fact.VSTDIFIN,0,19000101,
decode(substr(fact.VSTDIFIN,5),
'0230', substr(fact.VSTDIFIN,1,4)
|| '0301',fact.VSTDIFIN)),'yyyymmdd') ) DateRecente,
DECODE( virage_cont.id_cont,
null,add_months(sysdate,-7*12),
add_months(sysdate,-15*12)) dateLimite
FROM
FACTCAN.XC4DSAV fact
LEFT JOIN VIRAGE.CONTRAT virage_cont
on fact.VSTNOCNT_VIRAGE = virage_cont.NO_CONTR
where
fact.NUMERO_DOSSIER_STAR is not null ) t3
on e.ID_EVENEMENT = t3.NUMERO_DOSSIER_STAR
WHERE
t1.dateRecente < add_months(sysdate, -7*12)
AND t2.dateRecente < add_months(sysdate, -7*12)
AND virage_c.id_cont is null
AND t2.ID_PERSONNE_UNIVERS is not null
AND t1.ID_PERSONNE_STAR is null
AND t3.dateRecente < t3.dateLimite
FETCH
FIRST 1000 ROWS ONLY;
When I'm trying to get the results from an event with either
t1.ID_PERSONNE_STAR or t2.ID_PERSONNE_UNIVERS is null, the query isn't returning anything when it should in fact return some data. The is not null work as intended though. Any idea?

Answer 1

I updated the readability of the query. Also, as noted by others, you have to be careful about the WHERE clause. The issue you are probably running into is your where clauses for the T1, T2 and T3 for left-joins... Move these up to those joins... ex
where you have
left join (rest of the left-join subquery with alias ) t1
on t1.ID_EVENEMENT = E.ID_EVENEMENT
change to
on t1.ID_EVENEMENT = E.ID_EVENEMENT
AND t1.dateRecente < add_months(sysdate, -7*12)
This way, the date requirement is part of the LEFT-JOIN. By having that in the WHERE clause is turning it into an INNER JOIN.
You can leave the T1 "IS NULL" test at the where clause portion because you are explicitly expecting no matching records.
Check similar situations for your other left-joins... move the CRITERIA to the JOIN/ON clause and remove from the WHERE. The where clause SHOULD have the "IS NULL" for final expectation.