10. Persistence with Mapper

This chapter covers Connecting to a database Query constructs Relationships Entity validation

The vast majority of web applications that do anything semiuseful will ultimately need to store their data somewhere. Over the past decade or more, the relational database management system (RDBMS) has been the solution of choice for most developers, and the ANSI Structured Query Language (SQL) has become a standardized dialect for interacting with these databases. Although many database vendors have added and extended the ANSI version of SQL in several different directions, the core operations are still pretty much the same in any engine you choose to work with.