# Connection¶

An instance of class TYPO3\CMS\Core\Database\Connection is retrieved from the ConnectionPool by calling ->getConnectionForTable() and handing over the table name a query should executed on.

The class extends the basic Doctrine DBAL Doctrine\DBAL\Connection class and is mainly used internally within the TYPO3 CMS framework to establish, maintain and terminate connections to single database endpoints. Those internal methods are not scope of this documentation since an extension developer usually doesn’t have to deal with that.

For an extension developer however, the class provides a list of “short-hand” methods that allow dealing with “simple” query cases, without the complexity of the QueryBuilder. Using those methods typically ends up in rather short and easily readable code. The methods have in common that they support only “equal” comparisons in WHERE conditions, that all fields and values are fully quoted automatically and the created queries are executed right away.

Note

The Connection object is designed to work on a single table only. If queries to multiple tables should be performed, the object must not be re-used. Instead, a single Connection instance should be retrieved via ConnectionPool per target table. However, it is allowed to use one Connection object for multiple queries to the same table.

## insert()¶

Creates and executes an INSERT INTO statement. A (slightly simplified) example from the Registry API:

// use TYPO3\CMS\Core\Utility\GeneralUtility;
// use TYPO3\CMS\Core\Database\ConnectionPool;
// INSERT INTO sys_registry (entry_namespace, entry_key, entry_value) VALUES ('aoeu', 'aoeu', 's:3:\"bar\";')
GeneralUtility::makeInstance(ConnectionPool::class)
->getConnectionForTable('sys_registry')
->insert(
'sys_registry',
[
'entry_namespace' => $namespace, 'entry_key' =>$key,
'entry_value' => serialize($value) ] );  Well, that should be rather obvious: First argument is the table name to insert a row into, second argument is an array of key/value pairs. All keys are quoted to field names and all values are quoted to string values. It is possible to add another array as third argument to specify how single values are quoted. This is useful if date or numbers or similar should be inserted. The example below quotes the first value to an integer and the second one to a string: // use TYPO3\CMS\Core\Utility\GeneralUtility; // use TYPO3\CMS\Core\Database\ConnectionPool; // use TYPO3\CMS\Core\Database\Connection; // INSERT INTO sys_log (userid, details) VALUES (42, 'klaus') GeneralUtility::makeInstance(ConnectionPool::class) ->getConnectionForTable('sys_log') ->insert( 'sys_log', [ 'userid' => (int)$userId,
'details' => (string)$details, ], [ Connection::PARAM_INT, Connection::PARAM_STR, ] );  insert() returns the number of affected rows. Guess what? That’s the number 1 … In case something goes wrong a \Doctrine\DBAL\DBALException is raised. Note A list of allowed field types for proper quoting can be found in the TYPO3\CMS\Core\Database\Connection class and its base class \Doctrine\DBAL\Connection ## bulkInsert()¶ INSERT multiple rows at once: // use TYPO3\CMS\Core\Utility\GeneralUtility; // use TYPO3\CMS\Core\Database\ConnectionPool;$connection = GeneralUtility::makeInstance(ConnectionPool::class)
->getConnectionForTable('sys_log');
$connection->bulkInsert( 'sys_log', [ [(int)$userId, (string)$details1], [(int)$userId, (string)$details2], ], [ 'userid', 'details', ], [ Connection::PARAM_INT, Connection::PARAM_STR, ] );  First argument is the table to insert table into, second argument is an array of rows, third argument is the list of field names. Similar to ->insert() it is optionally possible to add another argument to specify quoting details, if omitted, everything will be quoted to strings. Note mysql is rather forgiving when it comes to insufficient field quoting: Inserting a string to an int field will not raise an error and mysql will adapt internally. However, other dbms are not that relaxed and may raise errors. It is good practice to specify field types for each field, especially if they are not strings. Doing so right away will reduce the number of raised bugs if people run your extension an anything else than mysql. ## update()¶ Create and execute an UPDATE statement. The example from FAL's ResourceStorage sets a storage to offline: // use TYPO3\CMS\Core\Utility\GeneralUtility; // use TYPO3\CMS\Core\Database\ConnectionPool; // use TYPO3\CMS\Core\Database\Connection; // UPDATE sys_file_storage SET is_online = 0 WHERE uid = '42' GeneralUtility::makeInstance(ConnectionPool::class) ->getConnectionForTable('sys_file_storage') ->update( 'sys_file_storage', ['is_online' => 0], ['uid' => (int)$this->getUid()],
[Connection::PARAM_INT]
);


First argument is the table an update should be executed on, the second argument is an array of key/value pairs to set, the third argument is an array of “equal” where statements that are combined with AND, the (optional) fourth argument specifies the type of values to be updated similar to ->insert() and bulkInsert().

Note the third argument WHERE foo = 'bar' only supports equal =. For more complex stuff the QueryBuilder has to be used.

The method returns the number of affected rows.

## delete()¶

Execute a DELETE query using equal conditions in WHERE, example from BackendUtility to mark rows as no longer locked by a user:

// use TYPO3\CMS\Core\Utility\GeneralUtility;
// use TYPO3\CMS\Core\Database\ConnectionPool;
// use TYPO3\CMS\Core\Database\Connection;
// DELETE FROM sys_lockedrecords WHERE userid = 42
GeneralUtility::makeInstance(ConnectionPool::class)
->getConnectionForTable('sys_lockedrecords')
->delete(
'sys_lockedrecords',
['userid' => (int)42],
[Connection::PARAM_INT]
);


First argument is the table name, second argument is a list of AND combined WHERE conditions as array, third argument specifies the quoting of WHERE values. There is a pattern ;)

Note

TYPO3 CMS uses a “soft delete” approach for many tables. Instead of directly deleting a rows in the database, a field - often called deleted - is set from 0 to 1. Executing a DELETE query circumvents this and really removes rows from a table. For most tables, it is better to use the DataHandler API to handle deletes instead of executing such low level queries directly.

## truncate()¶

Empty a table, removing all rows. Usually much quicker than a ->delete() of all rows. This typically resets “auto increment primary keys” to zero. Use with care:

// use TYPO3\CMS\Core\Utility\GeneralUtility;
// use TYPO3\CMS\Core\Database\ConnectionPool;
// TRUNCATE cache_treelist
GeneralUtility::makeInstance(ConnectionPool::class)
->getConnectionForTable('cache_treelist')
->truncate('cache_treelist');


## count()¶

A COUNT query. Again, this methods becomes handy if very simple COUNT statements are to be executed, the example returns tha number of active rows from table tt_content that have their bodytext field set to klaus:

// use TYPO3\CMS\Core\Utility\GeneralUtility;
// use TYPO3\CMS\Core\Database\ConnectionPool;
// SELECT COUNT(*)
// FROM tt_content
// WHERE
//     (bodytext = 'klaus')
//     AND (
//         (tt_content.deleted = 0)
//         AND (tt_content.hidden = 0)
//         AND (tt_content.starttime <= 1475621940)
//         AND ((tt_content.endtime = 0) OR (tt_content.endtime > 1475621940))
//     )
$connection = GeneralUtility::makeInstance(ConnectionPool::class)->getConnectionForTable('tt_content');$rowCount = $connection->count( '*', 'tt_content', ['bodytext' => 'klaus'] );  First argument is the field to count on, usually * or uid. Second argument is the table name, third argument is an array of WHERE equal conditions combined with AND. Remarks: • ->count() of Connection returns the number directly as integer, in contrast to the method of the QueryBuilder, there is no need to call ->fetchColumns(0) or similar. • The third argument expects all WHERE values to be strings, each single expression is combined with AND. • The RestrictionBuilder kicks in and adds additional WHERE conditions based on TCA settings. • Field names and values are quoted automatically. • If anything more complex than a simple equal condition on WHERE is needed, the QueryBuilder methods are a better choice: Next to ->select(), the ->count() query is often the least useful method of the Connection object. ## select()¶ Creates and executes a simple SELECT query based on equal conditions. Its usage is limited, the RestrictionBuilder kicks in and key/value pairs are automatically quoted: // use TYPO3\CMS\Core\Utility\GeneralUtility; // use TYPO3\CMS\Core\Database\ConnectionPool; // SELECT entry_key, entry_value FROM sys_registry WHERE entry_namespace = 'my_extension'$resultRows = GeneralUtility::makeInstance(ConnectionPool::class)
->getConnectionForTable('sys_registry')
->select(
['entry_key', 'entry_value'],
'sys_registry',
['entry_namespace' => 'my_extension']
);


Remarks:

• In contrast to the other short-hand methods, ->select() returns a Statement object ready to ->fetch() single rows or to ->fetchAll()
• The method accepts a series of further arguments to specify GROUP BY, ORDER BY, LIMIT and OFFSET query parts.
• For non-trivial SELECT queries, it is often better to switch to the according method of the QueryBuilder object.
• The RestrictionBuilder adds default WHERE restrictions. If those restrictions do not apply to the query needs, it is required to switch to the QueryBuilder->select() method for fine-grained WHERE manipulation.

## lastInsertId()¶

Returns the uid of the last ->insert() statement. Useful if this id needs to be used afterwards directly:

// use TYPO3\CMS\Core\Utility\GeneralUtility;
// use TYPO3\CMS\Core\Database\ConnectionPool;
// use TYPO3\CMS\Core\Database\Connection;
$connectionPool = GeneralUtility::makeInstance(ConnectionPool::class);$databaseConnectionForPages = $connectionPool->getConnectionForTable('myTable');$databaseConnectionForPages->insert(
'myTable',
[
'pid' => 0,
'title' => 'Home',
]
);
$pageUid = (int)$databaseConnectionForPages->lastInsertId('pages');


Remarks:

• ->lastInsertId($tableName) needs the table name as first argument. While this is optional, you should always supply the table name for DBAL compatibility with engines like postgres. • If the auto increment field name is not uid, the second argument with the name of this field must be supplied. For casual TYPO3 tables, uid is ok and the argument can be left out. ## createQueryBuilder()¶ The QueryBuilder should not be re-used for multiple different queries. However, it sometimes becomes handy to first fetch a Connection object for a specific table and to execute a simple query, and to create a QueryBuilder for a more complex query from this connection object later. The methods usefulness is limited however and no good example within the Core can be found at the time of this writing. The method can be helpful in loops to save some precious code characters, too: // use TYPO3\CMS\Core\Utility\GeneralUtility; // use TYPO3\CMS\Core\Database\ConnectionPool;$connection = GeneralUtility::makeInstance(ConnectionPool::class)->getConnectionForTable($myTable); foreach ($someList as $aListValue) {$myResult = \$connection->createQueryBuilder
->select('something')
->from('whatever')
->where(...)
->execute()
->fetchAll();
}