Quitter plusieurs tables avec des horodateurs

Question

Ok Les gourous SQL et Oracle J'ai une requête un peu compliquée que j'essaie de construire.

Voici ma requête en cours:

select distinct person_info.person_name 
    table2.value, 
    table3.value, 
    table4.value, 
    table5.value 
from person_info 
    left join table2 on table2.person_name=person_info.person_name 
    left join table3 on table3.person_name=person_info.person_name 
    left join table4 on table4.person_name=person_info.person_name 
    left join table5 on table5.person_name=person_info.person_name; 

La clé primaire pour chaque table est à la fois person_name et un timestamp. Maintenant, mon problème est que si plusieurs instances de la même person_name existent dans une table, je veux seulement left join sur le plus récent. Est-ce que quelqu'un sait comment ajouter ce comportement à cette requête? J'utilise Oracle.

Merci!

Answer 1

Essayez:

select distinct person_info.person_name 
    t2.value, 
    t3.value, 
    t4.value, 
    t5.value 
from person_info 
    left join (select t.*, row_number() over (partition by person_name order by timestamp_column desc) rowno from table2 t) t2 
     on t2.person_name=person_info.person_name and t2.rowno=1 
    left join (select t.*, row_number() over (partition by person_name order by timestamp_column desc) rowno from table3 t) t3 
     on t3.person_name=person_info.person_name and t3.rowno=1 
    left join (select t.*, row_number() over (partition by person_name order by timestamp_column desc) rowno from table4 t) t4 
     on t4.person_name=person_info.person_name and t4.rowno=1 
    left join (select t.*, row_number() over (partition by person_name order by timestamp_column desc) rowno from table5 t) t5 
     on t5.person_name=person_info.person_name and t5.rowno=1;