The goal is to build a search form that can be entered on multiple field searches. But entering all fields are optional.
What is the equivalent code in LINQ?
Thanks.

```
string str = "";
if(a!="")
    str += "f1 == a";
if(b!="")
    str += " && f2 == b";
if(c!="")
    str += " && f3 == c";

select f1, f2, f3 from p
where str;

```