F# query for "doesn't contain"

Question

There's a query to search for when an item is contained in a list, but there isn't one for when an item isn't.

This query finds customer objects which don't have ContactNum in the given list cdiffnums. What could I do to return just the customers that dont have a ContactNum in this list?

let q =
    query {
        for c in dc.Customers do
        where (query { for n in cdiffnums do contains c.ContactNum })
        select c
    }

Answer 1

My F# is rusty, but have you tried:

let q =
    query {
        for c in dc.Customers do
        where (not (query { for n in cdiffnums do contains c.ContactNum }))
        select c
    }