Question: Let's say you have parameters(s) in your LINQ query where clause, how do you handle that?

Here is an example:

```
var peoples= from i in individuals
  where (string.IsNullOrEmpty(lastName) i.LastName.Equals(lastName))
  select i;

```

Answer: 
[101 LinQ Samples](http://msdn.microsoft.com/en-us/vcsharp/aa336746.aspx) you can start with samples from MSDN
You do it in LINQ like you would do in "normal" C#.

In your sample you used string.IsNullOrEmpty(), so you don't differentiate between null and "". If that's the case you could write sth. like the following:

```
if ((lastName ?? "") == (i.LastName ?? ""))
{
   // equal
}

```

Note: [The ?? operator returns the left-hand operand if it is not null, or else it returns the right operand.](http://msdn.microsoft.com/en-US/library/ms173224%28VS.80%29.aspx)

You can integrate that logic into your LINQ query as follows:

```
var peoples = from i in individuals
              where (lastName ?? "") == (i.LastName ?? "")
              select i;

```