Updating access database
The drawback of this approach is the fact that it requires many JOINs or separate queries to retrieve all necessary data if a user needs to get the data for a single person.
Also, in order to insert new person that is physically split in several tables you would need to use transactions to update many table, and in many case we need to follow parent/child order defined by referential integrity, read primary key of the parent row before we insert child row, lock several tables, etc.
For example, to retrieve all the entries where the author’s name is the same as the blog name, we could issue the query: statement, the percent sign signifies a multiple-character wildcard and the underscore signifies a single-character wildcard.) This means things should work intuitively, so the abstraction doesn’t leak.
To create an object, instantiate it using keyword arguments to the model class, then call s for you automatically, behind the scenes.
Classic relational databases enable you to create highly normalized data models with schema that might contain a lot of tables.
Logical entities are broken into several tables and every complex property of the primary entity (for example, list, array, collection) is placed into separate table.
Both ends of a many-to-many relationship get automatic API access to the other end.
The API works similar to a “backward” one-to-many relationship, above.
To span a relationship, just use the field name of related fields across models, separated by double underscores, until you get to the field you want.