MySQL - Inner join into same table with WHERE clause

Question

I have a MySQL table called campaigns like the following

ID    integer
Name  text
isBalanced  boolean
redirects  tinyint

I am trying to achieve a SELECT query so that I get ALL the rows where isBalanced is false PLUS only a DEFINED number of rows where isBalanced is true. After I get this result I need to get the single one with the lowest number of redirects .

I know that there are ways to do it but I am having an hard time to figure out how. This is what I got until know

SELECT campaigns.id, campaigns.name, campaigns.isBalanced, campaigns.redirects
FROM campaigns AS c
INNER JOIN campaigns_2 AS c2
WHERE c.isBalanced = 0

However I am not able to select just some of them from the c2 set and then regroup all the filter to get the single one with lowest number of redirects .

Any help would be greatly appreciated.

Answer 1

It sounds like you want union all , perhaps with order by and limit :

select c.*
from campaigns c
where c.isBalanced = 0
union all
(select c.*
 from campaigns c
 where c.isBalanced = 1
 limit ??
)
order by redirects
limit 1;

The "defined number" goes where the ?? is.