NOT NULL Constraint
A NOT NULL constraint is functionally equivalent to the following check constraint with an IS NOT NULL predicate:
Some relational database management systems are able to optimize performance when the NOT NULL constraint syntax is used as opposed to the CHECK constraint syntax given above.
Read more about this topic: Check Constraint
Famous quotes containing the words null and/or constraint:
“A strong person makes the law and custom null before his own will.”
—Ralph Waldo Emerson (1803–1882)
“In America a woman loses her independence for ever in the bonds of matrimony. While there is less constraint on girls there than anywhere else, a wife submits to stricter obligations. For the former, her father’s house is a home of freedom and pleasure; for the latter, her husband’s is almost a cloister.”
—Alexis de Tocqueville (1805–1859)