Tuesday, October 16, 2012

Check Constraint

CHECK constraints are that they are not restricted to a particular column. They may also check that any combination of column values meets a criterion. The constraint is defined using the same rules that you would use in a WHERE clause. Once the check defined, the database will only insert a new row or update an existing row if the new value satisfies the CHECK constraint. The CHECK constraint is used to ensure data quality.

create table employees
(
imployeeid int check(employeeid >0)

Lname nvarchar(20),
Fname nvarchar(20)

)

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