lengthb(string) Calculates the length in bytes occupied by string: returns the length of the string in bytes
length(string) Calculates the length of characters occupied by string: returns the length of the string in characters
For single-byte characters, LENGTHB and LENGTH are the same.
For example, length('string')=lengthb('string') can be used to judge whether the string contains Chinese.
Note:
How many bytes a Chinese character occupies in the Oracle database is related to the character set of the database. In UTF8, the length is three.
select length('cctv') from dual ; query how many bytes Chinese characters occupy in the Oracle database