Updating the child table

I have a relationship table in between two tables which needs to be updated when i update one table. For example TableA(id,name) Relation(TableA_id,TableB_id) 开发者_运维技巧TableB(id,name). How to update the table Relation while updating the TableA?

Did you set has_and_belongs_to_many in your models of TableA and TableB ?