Subtract timestamp

[Neeraja005]

Hello everyone,

I want to fetch Interval between 2 different dates with one customer id.

Please look into the image for a quick overview.

I have 2 types for one customer  type='Q' and 'A'

I need to subtract the approved date with type Q  and create_date  with type A  where appointment_date for both = Nul or 0

I am trying to use the following formula: 

Spoiler

=Interval((if (type='Q' and customer_id=customer_id and (len(Trim(appointment_date))=0),approvedAt))-(if (type='A' and customer_id=customer_id and (len(Trim(appointment_date))=0),[message.createdAt])),'D hh:mm')

Can someone please help me with this. Anykind of information would be helpful

TIA

Regards,

Neeraja Upadrasta