Syntax
------ 
LENGTH(str)
 
Description
----------- 
Returns the length of the string str, measured in bytes. A
multi-byte
character counts as multiple bytes. This means that for a
string
containing five two-byte characters, LENGTH() returns 10,
whereas
CHAR_LENGTH() returns 5. 
 
If str is not a string value, it is converted into a string.
If str is NULL, the function returns NULL.
 
Until MariaDB 10.3.1, returns MYSQL_TYPE_LONGLONG, or
bigint(10), in all cases. From MariaDB 10.3.1, returns
MYSQL_TYPE_LONG, or int(10), when the result would fit
within 32-bits.
 
Oracle Mode
 
When running Oracle mode from MariaDB 10.3, LENGTH() is a
synonym for CHAR_LENGTH().
 
Examples
-------- 
SELECT LENGTH('MariaDB');
+-------------------+
| LENGTH('MariaDB') |
+-------------------+
| 7 |
+-------------------+
 
SELECT LENGTH('π');
+--------------+
| LENGTH('π') |
+--------------+
| 2 |
+--------------+
 
In Oracle mode from MariaDB 10.3:
 
SELECT LENGTH('π');
+--------------+
| LENGTH('π') |
+--------------+
| 1 |
+--------------+
 


URL: https://mariadb.com/kb/en/length/