Join or Union All To Combine Records?

Question

I have 2 similar tables that contain campaign names. I know I can do an union all to combine the tables, but I was wondering if there was a way to do this using form of Join instead? I want to create a table Z with campaign names for table A plus campaign names from table B (which are not in A). Can I do this with a join or is Union ALL the only way?

Answer 1

SELECT * INTO TABLEZ
FROM 
  (
    SELECT Column1, Column2, Column3.... FROM TABLEA 
    UNION ALL
    SELECT Column1, Column2, Column3.... FROM TABLEB
  )Q

Answer 2

UNION is the easier and correct way to do that. Purely for the exercise you can do it with a JOIN but it is a lot more complex, unreadable, and the perf will be way worse...

Answer 3

Here is how you would do this with a full outer join :

select distinct coalesce(a.campaign, b.campaign)
from b left outer join
     a
     on a.campaign = b.campaign;

The union / union all approach is totally reasonable. I'm just offering this as a join solution that you seem to be alluding to in the question.