src/ActiveQuery.php
public function count($q = '*', $db = null)
    {
        if ($this->emulateExecution) {
            return 0;
        }

        if ($this->where === null) {
            /* @var $modelClass ActiveRecord */
            $modelClass = $this->modelClass;
            if ($db === null) {
                $db = $modelClass::getDb();
            }

            return $db->executeCommand('LLEN', [$modelClass::keyPrefix()]);
        } else {
            return $this->executeScript($db, 'Count');
        }
    }
public function count($q = '*', $db = null)
    {
        if ($this->emulateExecution) {
            return 0;
        }

        if ($this->where === null) {
            /* @var $modelClass ActiveRecord */
            $modelClass = $this->modelClass;
            if ($db === null) {
                $db = $modelClass::getDb();
            }

            return $db->executeCommand('LLEN', [$modelClass::keyPrefix()]);
        } else {
            return $this->executeScript($db, 'Count');
        }
    }
Returns the number of records.
@param string $q the COUNT expression. This parameter is ignored by this implementation.
@param Connection $db the database connection used to execute the query.
If this parameter is not given, the `db` application component will be used.
@return int number of records