Doctrine_manual-1-2-en

Chapter 20: Database Abstraction Layer 292
Chapter 20
Database Abstraction Layer
The Doctrine Database Abstraction Layer is the underlying framework that the ORM uses to
communicate with the database and send the appropriate SQL depending on which database
type you are using. It also has the ability to query the database for information like what table
a database has or what fields a table has. This is how Doctrine is able to generate your
models from existing databases so easily.
This layer can be used independently of the ORM. This might be of use for example if you
have an existing application that uses PDO directly and you want to port it to use the Doctrine
Connections and DBAL. At a later phase you could begin to use the ORM for new things and
rewrite old pieces to use the ORM.
The DBAL is composed of a few different modules. In this chapter we will discuss the
different modules and what their jobs are.
Export
The Export module provides methods for managing database structure. The methods can be
grouped based on their responsibility: create, edit (alter or update), list or delete (drop)
database elements. The following document lists the available methods, providing examples
of their use.
Introduction
Every schema altering method in the Export module has an equivalent which returns the SQL
that is used for the altering operation. For example createTable() executes the query /
queries returned by createTableSql().
In this chapter the following tables will be created, altered and finally dropped, in a database
named events_db:
events
Name Type Primary Auto Increment
id integer true true
name string(255) false false
datetime timestamp false false
people
Name Type
Primary Auto Increment
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