Data Modeling and Persistence
Applications need a way of storing and manipulating data. That is what databases are for. Databases let you store, structure, retrieve and manage data.
Database basics
Databases put data that belong together in tables. Each table has multiple entries called rows. Each row can have multiple fields.
You can link tables using fields by creating a field in one table and referencing that field from another table. These fields are used to create relationships between tables: that’s why they’re called relational databases.