使用联接而不是全部执行联盟

Question

We are having a requirement where in we are trying to perform union operation for the tables of 2 different databases using informatica cloud, we dont have union transformation in it. So trying to explore if this can be performed using a left/full outer join ?

select * from t join p on t.id = p.id
union
select * from t join p on t.id = p.id2

Note: Not Union ALL only Union

Answer 1

The difference between union and union all is simply the removal of distinct values. The answer to your question is that you can emulate union using a bunch of coalesce() statements, select distinct , and full join .

However, why not just do:

select *
from t join
     p
     on t.id in (p.id, p.id2);

Depending on the data, you might need select distinct :

select distinct *
from t join
     p
     on t.id in (p.id, p.id2);