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public interface ForeignMultiKeyNullifier
The interface implemented for setting multi-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.setForeignMultiKeyNullifier(com.sleepycat.db.ForeignMultiKeyNullifier).
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, com.sleepycat.db.DatabaseEntry, 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 or SecondaryMultiKeyCreator for many-to-many, one-to-many, many-to-one and
 one-to-one relationships.
| Method Summary | |
|---|---|
|  boolean | nullifyForeignKey(SecondaryDatabase secondary,
                  DatabaseEntry key,
                  DatabaseEntry data,
                  DatabaseEntry secKey)Sets the foreign key reference to null in the datum of the primary database. | 
| Method Detail | 
|---|
boolean nullifyForeignKey(SecondaryDatabase secondary,
                          DatabaseEntry key,
                          DatabaseEntry data,
                          DatabaseEntry secKey)
                          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.key - the existing primary key.  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.secKey - the secondary key to be nullified.  This parameter is
 needed for knowing which key to nullify when multiple keys are present,
 as when SecondaryMultiKeyCreator is used.
DatabaseException - if an error occurs attempting to clear the key
 reference.| 
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