mysqli

Use MySQL as a database with mysqli*() functions in php.
Transactions will not be processed since DB file is created in myisam

mysql

Use MySQL as a database with mysql*() functions in php.
Transactions will not be processed since DB file is created in myisam.

mysql_innodb

Use MySQL as a database with innodb.
Transactions will be processed with innodb

cubrid

Use CUBRID as a database. See Manual for more info