function DatabaseConnection_sqlite::nextId

File

includes/database/sqlite/database.inc, line 302

Class

DatabaseConnection_sqlite

Specific SQLite implementation of DatabaseConnection.

Code

public function nextId($existing_id = 0) {
  $transaction = $this->startTransaction();
  // We can safely use literal queries here instead of the slower query
  // builder because if a given database breaks here then it can simply
  // override nextId. However, this is unlikely as we deal with short strings
  // and integers and no known databases require special handling for those
  // simple cases. If another transaction wants to write the same row, it will
  // wait until this transaction commits.
  $stmt = $this->query('UPDATE {sequences} SET value = GREATEST(value, :existing_id) + 1', array(
    ':existing_id' => $existing_id,
  ));
  if (!$stmt->rowCount()) {
    $this->query('INSERT INTO {sequences} (value) VALUES (:existing_id + 1)', array(
      ':existing_id' => $existing_id,
    ));
  }
  // The transaction gets committed when the transaction object gets destroyed
  // because it gets out of scope.
  return $this->query('SELECT value FROM {sequences}')
    ->fetchField();
}