UUID() returns a number that is globally unique in space and time. : UUID « Miscellaneous Functions « MySQL Tutorial

1. MySQL Tutorial
2. Miscellaneous Functions
3. UUID

mysql>
mysql> SELECT UUID();
+--------------------------------------+
| UUID()                               |
+--------------------------------------+
| 14185158-8adb-102a-8f5c-03475dfdde5e |
+--------------------------------------+
1 row in set (0.00 sec)

mysql>