Microsoft® SQL Server 2012 Unleashed

Cursors and Performance

In contrast to most other programming languages, SQL is a set-based processing language. You retrieve sets of rows, update sets of rows, and delete sets of rows. The set of rows affected is determined by the search conditions specified in the query. Unfortunately, most programmers are used to doing record-oriented operations on data and often want to apply the same technique to SQL Server data. Admittedly, at times, processing rows as a single result set with a single query can seem difficult or impossible. However, because of the performance implications, cursors should not be used just because it’s easier to program that way.

Note

SQL Server 2012 supports the MERGE statement, which provides another set-oriented option ...