| 
 | Berkeley DB version 5.3.28 | |||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||
public interface ForeignKeyNullifier
The interface implemented for setting single-valued foreign keys to null.
A key nullifier is used with a secondary database that is configured to
 have a foreign key integrity constraint and a delete action of ForeignKeyDeleteAction.NULLIFY.  The key nullifier is specified by calling
 SecondaryConfig.setForeignKeyNullifier(com.sleepycat.db.ForeignKeyNullifier).
When a referenced record in the foreign key database is deleted and the
 foreign key delete action is NULLIFY, the nullifyForeignKey(com.sleepycat.db.SecondaryDatabase, com.sleepycat.db.DatabaseEntry) method is called.  This method sets
 the foreign key reference to null in the datum of the primary database.  The
 primary database is then updated to contain the modified datum.  The result
 is that the secondary key is deleted.
SecondaryKeyCreator for
 many-to-one and one-to-one relationships.  It may not be used with
 SecondaryMultiKeyCreator because the secondary key is not passed as
 a parameter to the nullifyForeignKey method and this method would not know
 which key to nullify.  When using SecondaryMultiKeyCreator, use
 ForeignMultiKeyNullifier instead.
| Method Summary | |
|---|---|
|  boolean | nullifyForeignKey(SecondaryDatabase secondary,
                  DatabaseEntry data)Sets the foreign key reference to null in the datum of the primary database. | 
| Method Detail | 
|---|
boolean nullifyForeignKey(SecondaryDatabase secondary,
                          DatabaseEntry data)
                          throws DatabaseException
secondary - the database in which the foreign key integrity
 constraint is defined. This parameter is passed for informational
 purposes but is not commonly used.data - the existing primary datum in which the foreign key
 reference should be set to null.  This parameter should be updated by
 this method if it returns true.
DatabaseException - if an error occurs attempting to clear the key
 reference.| 
 | Berkeley DB version 5.3.28 | |||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | |||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | |||||||||