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Data & Analytics · Foundational

Default Constraint

A constraint that supplies a value for a column when an INSERT does not specify one.

Definition

DEFAULT values are applied only when the column is omitted from the INSERT (or the DEFAULT keyword is used), not when NULL is supplied explicitly. Common defaults are the current timestamp, zero or a status flag.

Example

CreatedAt DATETIME2 DEFAULT SYSUTCDATETIME()

Exam tip

Explicitly inserting NULL overrides a default; the default fires only when the column is left out.

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