Mysql——比较运算符

• [not] between...and... [不] 在范围之内。
• [not] in() [不] 在列出值范围内。
• is [not] null [不] 为空。

1.[not] between...and...

[不] 在范围之内。

mysql> select 1 between 15 and 20;
+---------------------+
| 1 between 15 and 20 |
+---------------------+
|                   0 |
+---------------------+

mysql> select 15 between 15 and 20;
+----------------------+
| 15 between 15 and 20 |
+----------------------+
|                    1 |
+----------------------+

mysql> select 16 not between 15 and 20;
+--------------------------+
| 16 not between 15 and 20 |
+--------------------------+
|                        0 |
+--------------------------+

2.[not] in()

[不] 在列出值范围内。

mysql> select 15 in (5,10,15,20);
+--------------------+
| 15 in (5,10,15,20) |
+--------------------+
|                  1 |
+--------------------+

mysql> select 16 in (5,10,15,20);
+--------------------+
| 16 in (5,10,15,20) |
+--------------------+
|                  0 |
+--------------------+

mysql> select 15 not in (5,10,15,20);
+------------------------+
| 15 not in (5,10,15,20) |
+------------------------+
|                      0 |
+------------------------+

3.is [not] null

[不] 为空。

mysql> select null is null;
+--------------+
| null is null |
+--------------+
|            1 |
+--------------+

mysql> select '' is null;
+------------+
| '' is null |
+------------+
|          0 |
+------------+

mysql> select 0 is null;
+-----------+
| 0 is null |
+-----------+
|         0 |
+-----------+

mysql> select null is not null;
+------------------+
| null is not null |
+------------------+
|                0 |
+------------------+