/**
* Creates a query to rollback a previously started transaction.
* @method update
* @param {array} $criteria The criteria to use, for sharding
* @return {Db_Query_Mysql} The resulting Db_Query object
*/
function rollback($criteria = null)
{
$query = new Db_Query_Mysql($this, Db_Query::TYPE_ROLLBACK, array('ROLLBACK' => true));
$query->rollback($criteria);
return $query;
}
/**
* Creates a query to select fields from a table. Needs to be used with {@link Db_Query::from()}.
*
* @param string|array $fields
* The fields as strings, or array of alias=>field
* @param string|array $tables
* The tables as strings, or array of alias=>table
* @return Db_Query_Mysql
* The resulting Db_Query object
*/
function select($fields, $tables)
{
if (empty($fields)) {
throw new Exception("Fields not specified in call to 'select'.");
}
if (empty($tables)) {
throw new Exception("Tables not specified in call to 'select'.");
}
$query = new Db_Query_Mysql($this, Db_Query::TYPE_SELECT);
return $query->select($fields, $tables);
}
