MySQL提供了两种检查boolean列真值的方法，即column_variable = true和column_variable is true。我创建了一个表，插入了一些值并尝试了一些select语句。结果如下：

首先，我创建了此表：

mysql> create table bool_test (
    -> id int unsigned not null auto_increment primary key,
    -> flag boolean );
Query OK, 0 rows affected (0.13 sec)

然后我插入了4行：

mysql> insert into bool_test(flag) values (true),(false),(9),(null);

mysql> select * from bool_test;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
|  2 |    0 |
|  3 |    9 |
|  4 | NULL |

这是select我在此表上触发的所有查询：

mysql> select * from bool_test where flag;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
|  3 |    9 |
+----+------+
2 rows in set (0.49 sec)

mysql> select * from bool_test where flag = true;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
+----+------+
1 row in set (0.02 sec)

mysql> select * from bool_test where flag is true;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
|  3 |    9 |
+----+------+
2 rows in set (0.04 sec)

mysql> select * from bool_test where flag = false;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
+----+------+
1 row in set (0.01 sec)

mysql> select * from bool_test where flag is false;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
+----+------+
1 row in set (0.00 sec)

mysql> select * from bool_test where !flag;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
+----+------+
1 row in set (0.00 sec)

mysql> select * from bool_test where not flag;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
+----+------+
1 row in set (0.00 sec)

mysql> select * from bool_test where flag != true;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
|  3 |    9 |
+----+------+
2 rows in set (0.00 sec)

mysql> select * from bool_test where flag is not true;
+----+------+
| id | flag |
+----+------+
|  2 |    0 |
|  4 | NULL |
+----+------+
2 rows in set (0.00 sec)

mysql> select * from bool_test where flag != false;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
|  3 |    9 |
+----+------+
2 rows in set (0.04 sec)

mysql> select * from bool_test where flag is not false;
+----+------+
| id | flag |
+----+------+
|  1 |    1 |
|  3 |    9 |
|  4 | NULL |
+----+------+
3 rows in set (0.00 sec)

我的问题是：这是在建议使用is/ is not，当是明智的使用=/!= 与true/ false？哪一个是独立于供应商的？