How do you find if a value is present in a table ref

To elaborate further. The idea is to be able to show if the current user is related to the customer.

Tables

Customers 
Contacts - relates to Customers. Contains a field "access" that is of type "user".
Projects - relates to Customers

How can I show a field on a project that show if current user is related to the Customer?

Ive tried aggregated functions but theres only a few: first/last/concat/count -which doesnt bring me further.

I would think that I should make some sort of 

select Customers.Contacts where access = user()

Or something that works with array?

Thank you

Jesper

As I understand it the select is doing a table lookup unlrelated to the current so in the example I made here it would also require adding a relation to which customer I need contacts from. maybe the more "correct" approach is to do something with the collection that is received.

If I in the formular reference Customers.Contacts.access and concat it it shows only the users related to this customer. But how do I query this ?

I found a solution. Please let me know if this is the optimal:

let ret := false;
for contact in Customers.Contacts.access do
if contact.User = user() then ret := true end
end;
ret

Thank you

Jesper

Thanks Jacques - that was much faster :-)