Order valid if drop down when displayed column is not primary key

[pmansy]

I need a drop down on column “Customer” in the Order table based on the column “Name” in the customer table.
The customer table has 4 columns: Name, FirstName, LastName and Email where Email is the key.
The drop down in the Order table must be the list “Name” from the customer table, sorted by LastName, then by FirstName. ORDERBY does not work, because Name is not the key of the customer table. How can I get the sorted drop down when the column I want to see is not the key?