[takekoshinet]

When $db->transStart() is called before any query, an error occurs because connID is false.

An uncaught Exception was encountered

Type:        Error
Message:     Call to a member function autocommit() on boolean
Filename:    /path/to/project/system/Database/MySQLi/Connection.php
Line Number: 479

Lazy initialize calling is lacked on trans*()

[lonnieezell]

Good catch!