>> I don't think mine is so confusing as you suggest if you take a second
> to understand it. Maybe if you read it with some whitespace:
>>
>> select
>> if ('%d' = 'example-2.com',
>> IFNULL(
>> (select dest from aliases where addr =
> '%[email protected]'),
>> (select addr from users where addr = '%[email protected]')
>> ),
>> NULL)
>>
>
> You almost never want to return a NULL result to Postfix using a SQL lookup.
> This actually can mean an affirmative instead of a negative result.
Thank you for the tip.
> A better query might be:
> (SELECT dest from aliases where addr = '%[email protected]' AND '%d'
> =
> 'example.net') UNION
> (SELECT addr from users where addr = '%[email protected]' AND '%d' =
> 'example.net') LIMIT 1
Funny, I think I posted almost the same query earlier on. :)
And I like this version better because it seems more standardized SQL
> Postfix expects an empty set (i.e. no rows returned) if it is to respond
> negatively that a virtual alias does not exist.
> Returning NULL does not equal no rows returned.
Are you sure? I ask only because the query I posted above DOES work - it does
reject invalid addresses normally (for the primary or secondary domain or other
unrelated domains on the server). Maybe postfix even unintentionally gets a
NULL back, tries to do something with it but fails and ultimately produces the
same result?
