Thanks for the answer Sergey.

>An EXISTS subquery doesn't return any data so there's no reason to list any columns in it.
>
>>That conflicts with the rule-of-thumb: "Never use * when selecting, always specify the fields".
>>I know you are a very smart man, so I am wondering why you would do this.
>>Does it change performance or just reduce typing?
>>
>>Einar
>>
>>>I use '*' in subquery because the field list is irrelevant in this case.
>>>

IF NOT EXISTS(SELECT * FROM [MyTable] WHERE [PK] = @PK) ...

>>>