SQL LEN()


LEN() 函数

LEN() 函数返回文本字段中值的长度。

SQL LEN() 语法

SELECT LEN(column_name) FROM table_name;

MySQL 中函数为 LENGTH():

SELECT LENGTH(column_name) FROM table_name;

演示数据库

在本教程中,我们将使用 shulanxt 样本数据库。

下面是选自 “Websites” 表的数据:

+----+--------------+---------------------------+-------+---------+
| id | name         | url                       | alexa | country |
+----+--------------+---------------------------+-------+---------+
| 1  | Google       | https://www.google.cm/    | 1     | USA     |
| 2  | 淘宝          | https://www.taobao.com/   | 13    | CN      |
| 3  | 树懒学堂      | http://www.shulanxt.com/    | 4689  | CN      |
| 4  | 微博          | http://weibo.com/         | 20    | CN      |
| 5  | Facebook     | https://www.facebook.com/ | 3     | USA     |
| 7  | stackoverflow | http://stackoverflow.com/ |   0 | IND     |
+----+---------------+---------------------------+-------+---------+

SQL LEN() 实例

下面的 SQL 语句从 “Websites” 表中选取 “name” 和 “url” 列中值的长度:

实例:

SELECT name, LENGTH(url) as LengthOfURL
FROM Websites;

输出结果:

mysql>SELECT name, LENGTH(url) as LengthOfURL
     ->FROM Websites;
+--------------+-------------+
| name         | LengthOfURL |
+--------------+-------------+
| Google       |      22     |
| 淘宝          |      23     |
| 树懒学堂      |      22     |
| 微博          |      17     | 
| Facebook     |      25      |
| stackoverflow |     25      |
+---------------+-------------+
6 rows in set(0.00 sec)