MySQL Tutorial/Information Functions/USER

To extract only the username part

mysql>
mysql> SELECT SUBSTRING_INDEX(USER(),"@",1);
+-------------------------------+
| SUBSTRING_INDEX(USER(),"@",1) |
+-------------------------------+
| root                          |
+-------------------------------+
1 row in set (0.00 sec)
mysql>

USER() returns the current MySQL username and hostname

mysql>
mysql> SELECT USER();
+----------------+
| USER()         |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql>