Using Hibernate as the persistence layer, I'm looking for a solution for the following scenario.

table A:
id int not null PK
field1 string null
field2 string null

table B:
id int not null PK
a_id int null
field1 string null
field2 string null

table B has a foreign key constraint attached to table A.id

table A data:
id field1 field2
1 string1 string2
2 string3 string4

table B data:
id a_id field1 field2
1 1 temp1 temp2
2 2 temp3 temp4
3 1 temp5 temp6

When table A with id=1 is deleted, how do I update table B with a_id=1 to a_id=null? I do not want to delete corresponding records of table B, I simply want to update the a_id values to "null".

Map A->B association as cascade="save-update" and before deleting of A instance call some kind of detach method to unbind correponding children objects of class B:


Interceptor or Lifecycle callback could help you to automate this. But I would prefer to put that code into DAO and use it everywhere I need this functionality.

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Leonid