Aggregates/Advanced SQL improvement (usage of

For some reason, when I need to lookup a certain ID based on a different attribute i have to create an advanced-query.
Furthermore I need to create a structure with 1 attribute which is the <entity>-identifier.
on the other hand, when I have a local variable, I can directly map it to an <entity>identifier.

strange...

Imho, this is a common pattern used very often (educated guess ;) )

so, what I like to see :

improvement of both queries to directly use the <entity>-identifier as a source/output structure