Doctrine mapping (ORM) with Database (DAL), Unidirectional vs Bidirectional.
Creating relationships inside a database is a very common thing for an web developer. Respecting to to RDBMS concept, we can create any sort of relationship inside a database. Things get changed when we have to use Doctrine for the mapping with database. Initially this made pretty much confused to me. Only after live working examples and few docs, I could able to get rid of it somehow. This post is about Doctrine mapping and difference between Unidirectional and Bidirectional relationship. What is Doctrine ? Doctrine is a set of PHP libraries that provides persistence services that is helpful managing PHP objects with Database layer. That means it creates a bridge between PHP light weight mapped objects and Database Objects. So Doctrine provides how to map PHP objects internally by its ORM (Object Relational Mapper) and its DB layer (DAL : Database Abstraction Layer) provides a unique object based query language(DQL : Doctrine Query Language) to write db queries independent of data...