(PHP 5 >= 5.0.5, PHP 7) Sets the default client character set

(PHP 5, PHP 7) Returns the MySQL client version as an integer

(PHP 5, PHP 7) Pings a server connection, or tries to reconnect if the connection has gone down

(PHP 5 >= 5.5.0, PHP 7) Starts a transaction

(PHP 5, PHP 7) Turns on or off auto-committing database modifications

(PHP 5, PHP 7) Returns the version of the MySQL server

(PHP 5, PHP 7) Selects the default database for database queries

(PHP 5, PHP 7) Changes the user of the specified database connection

(PHP 5, PHP 7) Returns the version of the MySQL protocol used

(PHP 5, PHP 7) Returns the thread ID for the current connection