Full outer join does not work when table 1 is empty

[baliyan_vinay]

Hello Community,

I am using the below table to get some data.

	select distinct
        nvl(a.key1,b.key1) as key1,
        nvl(a.key2,b.key2) as key2,
        nvl(a.key3,b.key3) as key3,
        a.data1
	b.data2
        from
        a
        Full Outer join
        b on
        a.key1=b.key1
	and a.key2=b.key2
        and a.key3=b.key3
        and b.indicator='O'
        and b.key1=25 and b.key2=3
        where
        and a.indicator='P'
        and a.key1=25 and a.key2=3
        order by nvl(a.key3,b.key3)

now this does not result in any data as table a is empty(No data for indicator P) but table b has data for indicator O.

What I wanted to do with this query is get the data, for cases where table a is empty, from table b and vice-versa and when both have data then two rows. 

Can you guys let me know what I am doing wrong here?

Thank you very much

[Vegar · Accepted solution]

What you are asking about is in SQL syntax, you might find better help searching SQL forums.

However, Qlik will perform the desired join if  you keep the join inside Qlik and not using SQL syntax. You could probably do something like this:

a:
SQL SELECT *
FROM a;

b:
LOAD * ;
SQL SELECT *
FROM b;

JOIN (b)
Load *
Resident a;

Drop table a;