Home Forums Article Discussions Article Discussions by Author Discuss content posted by Sergiy Table Variable RE: Table Variable

  • April 30, 2013 at 7:32 am

    #1611226

    Sean Lange (4/30/2013)

    I don't think I follow you here Tom. The condition checks is @ToCreate = 1. It does not equal 1 because it is NULL. Therefore the boolean check would be false.

    SQL uses three-valued logic, not true Boolean logic. Any comparison with a NULL (except when using IS [NOT] NULL) will not result in True or False, but in Unknown.

    For WHERE and IF, a logic result of True qualifies, and False and Unknown do not qualify.

    For CHECK constraints, a logic result of True or Unknown qualifies and False doesn't.

    Hugo Kornelis, SQL Server/Data Platform MVP (2006-2016)
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