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

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

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

(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 MySQL client version as an integer

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

(PHP 5, PHP 7) Returns a string representing the type of connection used

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