Snippet Name: Unique Constraint
Description: A unique constraint is a single field or combination of fields that uniquely defines a record. Some of the fields can contain null values as long as the combination of values is unique.
- In Oracle, a unique constraint can not contain more than 32 columns.
- A unique constraint can be defined in either a CREATE TABLE statement or an ALTER TABLE statement.
Note that Oracle does not permit you to create both a primary key and unique constraint with the same columns.
Also see: » Check Constraint: Create
» Primary Key Constraint
» Foreign Key Constraints
» Current_timestamp
» Deferring Constraint Checking
» Add Primary Key Constraint example
» Constraint Checks
» Add constraint example
Comment: (none)
Language: PL/SQL
Highlight Mode: PLSQL
Last Modified: March 07th, 2009
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