>>>>Yes, it should be a LEFT JOIN (was a typo, I assume). Check this link http://blogs.lessthandot.com/index.php/DataMgmt/DataDesign/the-ten-most-asked-sql-server-questions--1#4
>>>
>>>
>>>bu-bu-but i like number 3 and number 1 must i use number 2?
>>
>>No. Unless your field accepts null, you don't have to do that.
>>Cetin
>
>Are you saying it's a common misconception that LEFT JOIN is the fastest method?

No I didn't say that. For "this task" I don't think someone said it was the fastest method (I heard it from you). Think of it, it first does what "in" or "Exists" would do and then filter the result.
Cetin