The variable name var_name may consist of alphanumeric characters from the current character set, '.','_', and $.
One way to set a user-defined variable is by issuing a SET statement:
SET @var_name = expr [, @var_name = expr] ...
mysql>
mysql> SET @t1=0, @t2=1, @t3=2;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> select @t1;
+------+
| @t1 |
+------+
| 0 |
+------+
1 row in set (0.00 sec)
mysql> select @t2;
+------+
| @t2 |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
mysql> select @t3;
+------+
| @t3 |
+------+
| 2 |
+------+
1 row in set (0.00 sec)
mysql>