MySQL allows records longer than varchar(N) We have a database with a field of type VARCHAR(255) but in it I can see some records having a length of larger than 255, such as 264. How can it be possible? Can it be that the database is corrupt? Or somehow MySQL allows larger records? Or is there a known bug?

MySQL version: 5.5.47

Charset: utf8mb4
Use CHAR_LENGTH - you presumably have some > 1 byte characters and LENGTH returns bytes.

You can read more about the string functions in the manual:

MySQL 5.5 Reference Manual / Functions and Operators / String Functions