Kbase P66798: What is a Constraint
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
2/9/2004 |
|
Status: Unverified
GOAL:
What is a Constraint
FIX:
Part of an SQL table definition that restricts the values that can be stored in a table. When you insert, delete, or update column values, the constraint checks the new values against the conditions specified by the constraint. If the value violates the constraint, it generates an error. Along with Triggers, constraints enforce referential integrity by ensuring that a value stored in the foreign key of a table must either be null or be equal to some value in the matching unique or primary key of another table.