mysql>
mysql> SELECT SIGN(-32);
+-----------+
| SIGN(-32) |
+-----------+
| -1 |
+-----------+
1 row in set (0.00 sec)
mysql>
mysql> SELECT SIGN(0);
+---------+
| SIGN(0) |
+---------+
| 0 |
+---------+
1 row in set (0.00 sec)
mysql>
mysql> SELECT SIGN(234);
+-----------+
| SIGN(234) |
+-----------+
| 1 |
+-----------+
1 row in set (0.00 sec)
mysql>