Create "not exists" filter on tickets

Secenario:

- 2 person network team
- glpi has group "network"
- helpdesk assigns network related tickets to group "network"

There is currently no way to filter tickets such that:
- ticket is assigned to group "network"
- none of the two network technicians are assigned by name

Note other groups/users could also be assigned to this ticket and actively work on it so the naive solution of "group network and user is ---" does not work.

AFAIK you cannot express this kind of condition in a simple where clause. You'd need to use NOT EXISTS, a subquery or fiddle with JOIN clauses.

PS. the way "NOT" filters work currently is rather non user friendly - you need to first understand how the underlying query is constructed and that conditions are applied before aggregation, to make sense of the results. One may think applying somthing like "AND NOT assigned technician is john.doe" would discard tickets where john.doe is assigned - but it won't :)