class Truncate in Drupal 9

General class for an abstracted TRUNCATE operation.

Hierarchy

• class \Drupal\Core\Database\Query\Query implements PlaceholderInterface
  • class \Drupal\Core\Database\Query\Truncate

4 files declare their use of Truncate

Connection.php in core/lib/Drupal/Core/Database/Connection.php

Truncate.php in core/lib/Drupal/Core/Database/Driver/sqlite/Truncate.php

Truncate.php in core/lib/Drupal/Core/Database/Driver/pgsql/Truncate.php

Truncate.php in core/tests/fixtures/database_drivers/module/corefake/src/Driver/Database/corefakeWithAllCustomClasses/Truncate.php

3 string references to 'Truncate'

Connection::getDriverClass in core/lib/Drupal/Core/Database/Connection.php

Gets the driver-specific override class if any for the specified class.

Connection::truncate in core/lib/Drupal/Core/Database/Connection.php

Prepares and returns a TRUNCATE query object.

ConnectionTest::providerGetDriverClass in core/tests/Drupal/Tests/Core/Database/ConnectionTest.php

Data provider for testGetDriverClass().

File

core/lib/Drupal/Core/Database/Query/Truncate.php, line 11

Namespace

Drupal\Core\Database\Query

class Truncate extends Query {

  /**
   * The table to truncate.
   *
   * @var string
   */
  protected $table;

  /**
   * Constructs a Truncate query object.
   *
   * @param \Drupal\Core\Database\Connection $connection
   *   A Connection object.
   * @param string $table
   *   Name of the table to associate with this query.
   * @param array $options
   *   Array of database options.
   */
  public function __construct(Connection $connection, $table, array $options = []) {
    $options['return'] = Database::RETURN_AFFECTED;
    parent::__construct($connection, $options);
    $this->table = $table;
  }

  /**
   * {@inheritdoc}
   */
  public function compile(Connection $connection, PlaceholderInterface $queryPlaceholder) {
    return $this->condition
      ->compile($connection, $queryPlaceholder);
  }

  /**
   * {@inheritdoc}
   */
  public function compiled() {
    return $this->condition
      ->compiled();
  }

  /**
   * Executes the TRUNCATE query.
   *
   * @return
   *   Return value is dependent on whether the executed SQL statement is a
   *   TRUNCATE or a DELETE. TRUNCATE is DDL and no information on affected
   *   rows is available. DELETE is DML and will return the number of affected
   *   rows. In general, do not rely on the value returned by this method in
   *   calling code.
   *
   * @see https://learnsql.com/blog/difference-between-truncate-delete-and-drop-table-in-sql
   */
  public function execute() {
    $stmt = $this->connection
      ->prepareStatement((string) $this, $this->queryOptions, TRUE);
    try {
      $stmt
        ->execute([], $this->queryOptions);
      return $stmt
        ->rowCount();
    } catch (\Exception $e) {
      $this->connection
        ->exceptionHandler()
        ->handleExecutionException($e, $stmt, [], $this->queryOptions);
    }
  }

  /**
   * Implements PHP magic __toString method to convert the query to a string.
   *
   * @return string
   *   The prepared statement.
   */
  public function __toString() {

    // Create a sanitized comment string to prepend to the query.
    $comments = $this->connection
      ->makeComment($this->comments);

    // In most cases, TRUNCATE is not a transaction safe statement as it is a
    // DDL statement which results in an implicit COMMIT. When we are in a
    // transaction, fallback to the slower, but transactional, DELETE.
    // PostgreSQL also locks the entire table for a TRUNCATE strongly reducing
    // the concurrency with other transactions.
    if ($this->connection
      ->inTransaction()) {
      return $comments . 'DELETE FROM {' . $this->connection
        ->escapeTable($this->table) . '}';
    }
    else {
      return $comments . 'TRUNCATE {' . $this->connection
        ->escapeTable($this->table) . '} ';
    }
  }

}

Members

Name	Modifiers	Type	Description	Overrides
Query::$comments	protected	property	An array of comments that can be prepended to a query.
Query::$connection	protected	property	The connection object on which to run this query.
Query::$connectionKey	protected	property	The key of the connection object.
Query::$connectionTarget	protected	property	The target of the connection object.
Query::$nextPlaceholder	protected	property	The placeholder counter.
Query::$queryOptions	protected	property	The query options to pass on to the connection object.
Query::$uniqueIdentifier	protected	property	A unique identifier for this query object.
Query::comment	public	function	Adds a comment to the query.
Query::getComments	public	function	Returns a reference to the comments array for the query.
Query::getConnection	public	function	Gets the database connection to be used for the query.
Query::nextPlaceholder	public	function	Gets the next placeholder value for this query object. Overrides PlaceholderInterface::nextPlaceholder
Query::uniqueIdentifier	public	function	Returns a unique identifier for this object. Overrides PlaceholderInterface::uniqueIdentifier
Query::__clone	public	function	Implements the magic __clone function.	1
Query::__sleep	public	function	Implements the magic __sleep function to disconnect from the database.
Query::__wakeup	public	function	Implements the magic __wakeup function to reconnect to the database.
Truncate::$table	protected	property	The table to truncate.
Truncate::compile	public	function
Truncate::compiled	public	function
Truncate::execute	public	function	Executes the TRUNCATE query. Overrides Query::execute	1
Truncate::__construct	public	function	Constructs a Truncate query object. Overrides Query::__construct
Truncate::__toString	public	function	Implements PHP magic __toString method to convert the query to a string. Overrides Query::__toString	1