FOREIGN KEY Column Constraint

Purpose

Column constraint to define a column as a Foreign Key for a parent table

Syntax

FOREIGN KEY [COLLATE <cCollateSequence>]

See Also

ALTER TABLE, CONSTRAINTS, CREATE TABLE

Description

A constraint is used to define rules that help to provide data integrity. Column constraints are specific to the column name specified. You must have ALTER privilege on the table. The table will be locked for EXCLUSIVE use during the operation.

The FOREIGN KEY column constraint is used to define the column as a Foreign Key for a parent table. A tag index is built on the specified column; it is given the same name as the column. More than one column in the table can be defined as a Foreign Key.

The optional COLLATE <cCollateSequence> clause is included for Visual FoxPro language compatibility only.

Example

CREATE TABLE orderitem;
  (ord_ref char(5) FOREIGN KEY,;
  item_ref char(5) PRIMARY KEY)

Products

Lianja, Lianja Server