Referential Integrity

The entries in a foreign key must correspond to the primary key values of a row in the referenced table.

Occasionally, some other unique column combination may be referenced instead of a primary key. The primary key or column (or set of columns) with a unique constraint is known as a candidate key. The referenced column or set of columns must be a candidate key and is called the referenced key.

• Loss of Referential Integrity
  SAP Sybase IQ provides protection against referential integrity loss.
• Foreign Keys
  Use the CREATE TABLE statement or ALTER TABLE statement to create foreign keys, as you do primary keys.
• Referential Integrity Violations
  SAP Sybase IQ supports referential integrity with RESTRICT action (the ANSI default) at the statement level.
• Enforcing Referential Integrity with Existing Unenforced Foreign Keys
  You can enforce referential integrity with unenforced foreign keys.
• Enforcing Referential Activity in a New Table
  Enforce referential integrity in a new table.
• Dropping a Foreign Key
  Drop a foreogn key from a table.