> SELECT <fields> FROM <tables> WHERE table1.field (+) = table2.field;
>
> This will return all appropriate rows in table1, even if no
> corresponding value exists in table2 (it'll list an empty value for that
> column in the output tuples if no value exists).
In order to do that you should put the (+) operator at the "possible nulls"
side of the equality. It should go this way:
SELECT <fields> FROM <tables> WHERE table1.field = table2.field (+);