Syntax
------

CONNECTION_ID()

Description
-----------

Returns the connection ID for the connection. Every connection (including
events) has an ID that is unique among the set of currently connected clients.

Until MariaDB 10.3.1, returns MYSQL_TYPE_LONGLONG, or bigint(10), in all
cases. From MariaDB 10.3.1, returns MYSQL_TYPE_LONG, or int(10), when the
result would fit within 32-bits.

Examples
--------

SELECT CONNECTION_ID();
+-----------------+
| CONNECTION_ID() |
+-----------------+
|               3 |
+-----------------+

URL: https://mariadb.com/kb/en/connection_id/