SQL Server IN vs. EXISTS Performance

Question

I\'m curious which of the following below would be more efficient?

I\'ve always been a bit cautious about using IN because I believe SQL Server turns th

Answer 1

To optimize the EXISTS, be very literal; something just has to be there, but you don't actually need any data returned from the correlated sub-query. You're just evaluating a Boolean condition.

So:

WHERE EXISTS (SELECT TOP 1 1 FROM Base WHERE bx.BoxID = Base.BoxID AND [Rank] = 2)

Because the correlated sub-query is RBAR, the first result hit makes the condition true, and it is processed no further.