Query.cs

List<Customer> ret;
using (var db = new SqlConnection(connstring))
{
    var sql =
        "select C.[Id], C.[Name], C.[Email], C.[Phone], A.CustomerId, A.Street, " +
        "A.City, A.Country, A.ZIPCode from customer C " +
        "inner join[Address] A on A.CustomerId = C.Id";

    ret = db.Query<Customer, Address, Customer>(sql, (customer, address) =>
    {
        customer.Address = address;
        return customer;
    }, splitOn: "CustomerId").ToList();
}