Having sum() trouble

Databases
1

It’s been a long time since someone helped me with the following query portion and I can’t remember what it actually does.
Does this make sense to anyone?

Thanks!

having sum(case when com.type=‘Conversation’
then 1 else 0 end) = 0
and sum(case when com.type in ( ‘Voicemail Sent’
, ‘Email Sent’)
then 1 else 0 end) = 0

2

yeah it does

it means the query won’t return any grouped rows which included one of these types

3

Instead of making two statements out of it, why not just include ‘Conversation’ in with the others in the com.type in (blah blah blah) ?