Friday, October 23, 2009

What is the CHECK constraint in SQL Server?

Business rule validation can be applied to a table by using CHECK constraint. CHECK constraint must be specified as a logical expression that evaluates either to TRUE or FALSE.
A CHECK constraint takes longer to execute as compared to NOT NULL, PRIMARY KEY, FOREIGN KEY or UNIQUE constraints. Thus CHECK constraint must be avoided if the constraint can de defined using NOT NULL, PRIMARY KEY, FOREIGN KEY constraints.

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