Introduction

TYPO3 CMS relies on storing its data in a relational database management system (RDBMS). The Doctrine DBAL component is used to enable connecting to different database management systems. Most used is still MySQL / MariaDB, but thanks to Doctrine others like PostgreSQL and SQLite are also an option.

The corresponding DBMS can be selected during installation.

This chapter gives an overview of the basic TYPO3 database table structure, followed by some information on upgrading and maintaining table and field consistency, and then deep dives into the programming API.

Doctrine DBAL

Database queries in TYPO3 are done with an API based on Doctrine DBAL. The API is provided by the system extension core which is always loaded and thus always available.

Extension authors can use this low-level API to manage query operations directly on the configured DBMS.

Doctrine DBAL is feature rich. Drivers for various target systems enable TYPO3 to run on a long list of ANSI SQL compatible DBMS. If used properly, queries created with this API are translated to the specific database engine by doctrine without an extension developer taking care of that specifically.

The API provided by the Core is basically a pretty small and lightweight facade in front of Doctrine DBAL that adds some convenient methods as well as some TYPO3 CMS specific sugar. The facade additionally provides methods to retrieve specific connection objects per configured database connection based on the table that is queried. This enables instance administrators to configure different database engines for different tables while this is transparent for extension developers.

Doctrine DBAL has been introduced with TYPO3 CMS version 8 and substitutes the old API based on $GLOBALS['TYPO3_DB']. Extension authors are encouraged to switch away from TYPO3_DB to the new API. A dedicated chapter helps with typical migration questions. With database abstraction being built in Doctrine DBAL the old and optional extensions dbal and adodb are obsolete.

This document does not outline each and every single method the API provides. It sticks to those that are commonly used in extensions and some parts like the rewritten schema migrator are left out since they are usually of little to no interest for extensions.

Understanding Doctrine DBAL and Doctrine ORM

Doctrine is a two-fold project with Doctrine DBAL being the low-level database abstraction and query building interface to specific database engines, while Doctrine ORM is a high-level object relational mapping on top of Doctrine DBAL.

The TYPO3 Core - only - implements the dbal part. Doctrine ORM is neither required nor implemented nor used at the time of this writing.

Low-level and high-level database calls

This documentation is about low-level database calls. In many cases it is better to use higher level API’s like the DataHandler or Extbase repositories and to let the framework handle persistence details internally.

Tip

Always remember the high-level database calls and use them when appropriate!

Credits

Implementing the Doctrine DBAL API into TYPO3 has been a huge project in 2016. Special thanks goes to awesome Mr. Morton Jonuschat for the initial design, integration and support and to more than 40 different people who actively contributed to migrate more than 1700 calls from TYPO3_DB-style to Doctrine within half a year. This was a huge community achievement, thanks everyone involved!