>>>>>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

Sergey said it as well.

Anyway, here are my results

SQL Server Execution Times:
   CPU time = 219 ms,  elapsed time = 968 ms. -- NOT IN

 SQL Server Execution Times:
   CPU time = 125 ms,  elapsed time = 365 ms. -- NOT EXISTS

 SQL Server Execution Times:
   CPU time = 171 ms,  elapsed time = 268 ms. -- LEFT JOIN

Second try:

SQL Server Execution Times:
   CPU time = 156 ms,  elapsed time = 337 ms.

 SQL Server Execution Times:
   CPU time = 141 ms,  elapsed time = 365 ms.

 SQL Server Execution Times:
   CPU time = 187 ms,  elapsed time = 277 ms.

The execution plan was different and it took 39% vs. 31 for first two cases, but as you see the actual elapsed time is less for the LEFT JOIN.

I ran the test on 500K Bid table and 100K Items table.