public interface ForeignKeyNullifier
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
When a referenced record in the foreign key database is deleted and the
foreign key delete action is
nullifyForeignKey(com.sleepycat.je.SecondaryDatabase, com.sleepycat.je.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.
SecondaryKeyCreatorfor many-to-one and one-to-one relationships. It may not be used with
SecondaryMultiKeyCreatorbecause 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
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.
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