FOREIGN KEY Constraints

FOREIGN KEY constraints work in conjunction with PRIMARY KEY or UNIQUE key constraints to enforce referential integrity among specified tables.

    To create a FOREIGN KEY constraint

• In SQL Enterprise Manager's Server Manager window, double-click the appropriate table, choose the Advanced Features button, and then choose the Foreign Keys tab.

  (For details, search for "constraints" in SQL Enterprise Manager Help.)

Or

• Use the CREATE TABLE or ALTER TABLE statement.

  For example:

  ALTER TABLE titles
  ADD
  CONSTRAINT FK_pub_id FOREIGN KEY (pub_id) REFERENCES publishers (pub_id)

  adds a FOREIGN KEY constraint to the titles table on the pub_id column.

  (For details, see the CREATE TABLE and ALTER TABLE statements in the Microsoft SQL Server Transact-SQL Reference.)