[2.0] C# Combining Collections Using AND

[señorbadger]

Hello, I think this is more of a maths issue but here goes...

I am trying to write a method where if i pass in a collection of a collection of "Customer" objects it will compare them by ID number to return a colleciton of objects using (AND) ie only if the ID number appears in all of them.

Example expected

Input:

clsCustomer[][]
|
|---------- clsCustomer[]
| |
| |----- clsCustomer {ID = 1; FORENAME = "BOB"...}
| |----- clsCustomer {ID = 2; FORENAME = "BILL"...}
| |----- clsCustomer {ID = 3; FORENAME = "JOHN"...}
|
|---------- clsCustomer[]
| |
| |----- clsCustomer {ID = 1; FORENAME = "BOB"...}
| |----- clsCustomer {ID = 2; FORENAME = "BILL"...}
| |----- clsCustomer {ID = 4; FORENAME = "Hannah"...}
| |----- clsCustomer {ID = 3; FORENAME = "JOHN"...}
|
|---------- clsCustomer[]
| |
| |----- clsCustomer {ID = 1; FORENAME = "BOB"...}
| |----- clsCustomer {ID = 4; FORENAME = "Hannah"...}
| |----- clsCustomer {ID = 5; FORENAME = "Vicky"...}
| |----- clsCustomer {ID = 3; FORENAME = "JOHN"...}

If this was fed into the method the collection below would be returned

clsCustomer[]

clsCustomer {ID = 1; FORENAME = "BOB"...}
clsCustomer {ID = 3; FORENAME = "JOHN"...}

because they appear in all of the input arrays

Any help would be appriciated, source code would be handy

Thanks all