Changing foreign keys - IBM DB2 9.7 for Linux, UNIX, and Windows

You can change foreign keys for your table or nickname. A foreign key is a column or set of columns in a table or nickname whose values are required to match at least one primary key value of a row of its parent table or nickname.

Before you begin

To alter a table with a foreign key, you must have at least one of the following privileges on the table to be altered:

ALTER privilege
CONTROL privilege
DBADM authority
ALTERIN privilege on the schema of the table

About this task

A referential constraint is the rule that the values of the foreign key are valid only if either:

They appear as values of a parent key (primary key).
Some component of the foreign key is null.

Procedure

To change foreign keys using the Control Center:
1. Open the Alter Table notebook if you are adding a unique key to a table: From the Control Center, expand the object tree until you find the Tables folder. Click the Tables folder. Any existing tables are displayed in the pane on the right side of the window. Right-click the table you want in the contents pane and select Alter from the pop-up menu. The Alter Table notebook opens. If you are altering a foreign key on a nickname, open the Alter Nickname notebook.
2. On the Keys page, select a foreign key and click Change. The Change Foreign Key window opens.
3. Optional: Select a different parent table or nickname.
4. Specify the schema and name of the new parent table or nickname.
5. Optional: Select a new foreign key.
6. Optional: Change the action specified for "on delete" and "on update".
7. Optional: Change the name of the constraint
To change foreign keys using the command line, use the ALTER TABLE statement.