Oracle outer join syntax

问题

I have a query that looks like this:

select *
from find fsc,
        let lf,
        cust cus,
        STRIKE ist
WHERE   fsc.id = lf.id
AND     ist.ID_old = fsc.ID_old
AND     lf.cust_id = cus.cust_id(+)

I know (+) is old syntax for a join, but I am not sure what it is actually doing to this query. Could someone explain this and show this query without the (+) in the where statement, using more modern join syntax?

回答1:

I believe you want this:

select *
from find fsc join
     let lf
     on fsc.id = lf.id join
     STRIKE ist
     on ist.ID_old = fsc.ID_old left join
     cust cus
     on lf.cust_id = cus.cust_id;

To be honest, the outer join is probably not necessary. Why would lf have a cust_id that is not valid? The only reasonable possibility is if the value is NULL.

来源：https://stackoverflow.com/questions/40021127/oracle-outer-join-syntax