Linq and where clauses

So I was watching some of the PDC talks and noticed that some people write where clauses like this..

var result = from item in source 
              where item.Name == "John"
              where item.Country == "UK"
              select item

rather than like this

var result = from item in source 
              where item.Name == "John" && item.Country == "UK"
              select item

And I was wondering why and if there is a difference in the final expression tree produced.

Cheers,

Stephen.

Not sure if this is what you asked and I didn't try Linq to SQL but atleast the IL produced is identical (inside Linqpad). I couldn't figure how to get an expression tree out of that into the expression tree visualizer that's in the VS 2008 C# samples. (I haven't really studied expression trees at all so hopefully you get better answer)

@PerfectPhase: Weird. I wouldn't have thought the first one would even compile. And just so you know, the "select item" part isn't needed.

Just for your information first one is more expensive than the second one as per performance wise. Becuase the second one translate into one function<TSource,Bool> while the first one transfer into three function.

@Ajain: Ah thought that might be the case.  I would have lingered on it, but it was Bart de Smet, and he really knows his linq

5 days ago, spivonious wrote

@PerfectPhase: And just so you know, the "select item" part isn't needed.

That isn't correct.  I get a "query body must end with a select clause or a group clause" error without it.

19 hours ago, joechung wrote

*snip*

That isn't correct.  I get a "query body must end with a select clause or a group clause" error without it.

Hmm, it appears to be invalid in C#. It works in VB. Yet another one of the mysteries of life.