Upgrade table and field definitions¶
Each extension in TYPO3 can provide the
ext_tables.sql file that defines
which tables and fields the extension needs. Gathering all
ext_tables.sql files thus defines the complete set of tables, fields and
indexes of a TYPO3 instance to unfold its full functionality. The
Analyze Database Structure section in the
Admin Tools > Maintenance backend module can compare the defined set
with the current active database schema and shows options to align these two by
adding fields, removing fields and so on.
When you upgrade to newer versions of TYPO3 or upgrade an extension, the data definition of tables and fields may have changed. The database structure analyzer detects such changes.
When you install a new extension, any change to the database is performed automatically. When upgrading to a new major version of TYPO3, you should normally go through the upgrade wizard, whose first step is to perform all necessary database changes:
If you want to perform minor updates, update extensions or generally check the functionality of your system, you can go to Admin Tools > Maintenance > Analyze Database Structure:
This tool collects the information from all
ext_tables.sql files of all
active extensions and compares them with the current database structure. Then it
proposes to perform the necessary changes, grouped by type:
creating new tables
adding new fields to existing tables
altering existing fields
dropping unused tables and fields
You can choose which updates you want to perform. You can even decide not to create new fields and tables, although that will very likely break your installation.
For more information about the process of upgrading TYPO3, see the Upgrade Guide.
The ext_tables.sql files¶
As mentioned above, all data definition statements are stored in files named
ext_tables.sql, which may exist in any extension.
The peculiarity is that these files may not always contain a complete and valid SQL data definition. For example, the "dashboard" system extension defines a new table for storing dashboards:
CREATE TABLE be_dashboards ( identifier varchar(120) DEFAULT '' NOT NULL, title varchar(120) DEFAULT '' NOT NULL, widgets text );
This is a complete and valid SQL data definition. However, the community
extension "news" extends the
tt_content table with additional fields. It
also provides these changes in the form of a SQL
CREATE TABLE statement:
CREATE TABLE tt_content ( tx_news_related_news int(11) DEFAULT '0' NOT NULL, KEY index_newscontent (tx_news_related_news) );
The classes which take care of assembling the complete SQL data definition will
compile all the
CREATE TABLE statements for a given table and turn them
into a single
CREATE TABLE statement. If the table already exists,
missing fields are isolated and
ALTER TABLE statements are proposed
This means that as an extension developer you should always only have
CREATE TABLE statements in your
ext_tables.sql files, the system
will handle them as needed.