Dynamic query in LINQ

Question

How do I write a dynamic query for Linq, if I have say Customer class which holds the fields:

string name
string address
int phoneno

I have to

Answer 1

Here you go:

var result = from customer in Customers
             where string.IsNullOrEmpty(phoneNo) || customer.PhoneNo == phoneNo
             where string.IsNullOrEmpty(address) || customer.Address == address
             select customer;

If you're concerned that this generate the optimal SQL query underneath, as always you should attach a SQL Query Analyzer and check. But I believe the expression parser in Linq To Sql will collapse down the where clauses as appropriate based on the value of the arguments.