Many types of problems require you to analyze samples of data in sequences, looking for valuable information in data organized according to some order. For example, you might want to analyze sales figures over a time series, stock rates against a series of prices, or test results against a series of ratings. Most SQL Server 2000 procedures that analyze samples of data over a sequence can be very slow because they use cursors and set-based techniques. Now, SQL Server 2005 provides recursive common table expressions (CTEs) that greatly speed up analysis. (For an overview of recursive CTEs, see "Get in the Loop with CTEs,"April 2004, InstantDoc ID 42072.)

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