I'm running SQL Server 2000 and need to see whether a particular value exists in a table. Which is more efficient, using an EXISTS check or a SELECT COUNT(*)?

A Using the T-SQL EXISTS keyword to perform an existence check is almost always faster than using COUNT(*). EXISTS can stop as soon as the logical test proves true, but COUNT(*) must count every row, even after it knows one row has passed the test. Let's walk through a simple example to illustrate this point.

Ru...