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;

示例

"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  | 菜鸟教程      | http://www.runoob.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     |
+----+---------------+---------------------------+-------+---------+

从 "Websites" 表中选取 "name" 和 "url" 列中值的长度：

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            |
| 菜鸟教程     |    22             |
| 微博         |     17           |
| Facebook     |        25        |
| stackverflow |        25        |
+-------------+-------------------+