February 2013 - SQLPerformance.com
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The Halloween Problem – Part 3

 Posted by on February 18, 2013  4 Responses »
Feb 182013

The MERGE statement (introduced in SQL Server 2008) allows us to perform a mixture of INSERT, UPDATE, and DELETE operations using a single declarative statement. The Halloween Protection issues for MERGE are, logically enough, mostly a combination of the requirements for the individual operations performed, but there are some important differences and a couple of optimizations that apply only to MERGE.

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