Syntax
LENGTH(str)
Purpose
LENGTH() returns the length of str in bytes.
A multi-byte character is counted as multiple characters. For example, if you enter five two-byte characters, CHAR_LENGTH() returns 5, while LENGTH() returns 10.
Examples
obclient> SELECT LENGTH('CN'), LENGTH('hello');
+------------------+-----------------+
| LENGTH ('CN') | LENGTH('hello') |
+------------------+-----------------+
| 6 | 5 |
+------------------+-----------------+
1 row in set