mysql>
mysql> SELECT 2+1;
+-----+
| 2+1 |
+-----+
| 3 |
+-----+
1 row in set (0.00 sec)
mysql>
mysql> SELECT 4-2/4;
+--------+
| 4-2/4 |
+--------+
| 3.5000 |
+--------+
1 row in set (0.00 sec)
mysql>
mysql> SELECT 4-(2/4);
+---------+
| 4-(2/4) |
+---------+
| 3.5000 |
+---------+
1 row in set (0.00 sec)
mysql>