The Foreign Keys
tab is divided into two
sections, one with a list of foreign keys and one with various
dialog boxes for foreign key settings.
To add a foreign key, click the +
(plus) button below the foreign key list. A dialog box prompts
for a foreign key name and the new foreign key is created.
Under Windows, you can change the automatically generated
foreign key name by using the Options
dialog window. For more information, see
Section 11.4, “Editors”.
To drop a foreign key, select the foreign key and click the – (minus) button below the foreign key list.
You can modify the name of the foreign key, its ON
DELETE
, and its ON UPDATE
actions
using the dialog boxes provided in the Foreign Key
Settings section of the tab.
The options are:
NO ACTION
RESTRICT
CASCADE
SET NULL
To establish a foreign key relationship, choose a table from
the Ref. Table drop-down list. (Under
Linux this list box is called Refer.
Table.) The fields that can be related to create a
foreign key are listed in the frame below the drop-down list.
This frame contains two columns; one labeled
Column
and the other Reference
Column
. To select a column as a foreign key, double
click the area below Column and select a
column from the drop-down list. Alternately, drag a column
from the column editor to the Column
section. To add a related column from the referenced table,
double click the area below Reference
Column and select the related column from the
drop-down list.