How to show a variable ?

MySQL is known for its possibility of storing and requesting the data. But it can also use the variables. To display one variable in MySQL, a simple SELECT suffices:

mysql> SET @hello = "World !";
Query OK, 0 rows affected (0,00 sec)

mysql> SELECT @hello;
+---------+
| @hello  |
+---------+
| World ! |
+---------+
1 row in set (0,00 sec)