MySQLでフリップフロップ

以下のようなSQL文で、0と1を交互に入れ替えることができる。

UPDATE flip_flop SET value = value xor 1;

例

mysql> CREATE TABLE flip_flop (value int not null);
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO flip_flop VALUES (0);
Query OK, 1 row affected (0.00 sec)

mysql> SELECT * FROM flip_flop;
+-------+
| value |
+-------+
|     0 |
+-------+
1 row in set (0.00 sec)

mysql> UPDATE flip_flop SET value = value xor 1;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT * FROM flip_flop;
+-------+
| value |
+-------+
|     1 |
+-------+
1 row in set (0.00 sec)

mysql> UPDATE flip_flop SET value = value xor 1;
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> SELECT * FROM flip_flop;
+-------+
| value |
+-------+
|     0 |
+-------+
1 row in set (0.00 sec)