[NATIONAL] VARCHAR(M) [CHARACTER SET charset_name] [COLLATE collation_name]
A variable-length string. M represents the maximum column length in characters. The range of M is 0 to 65,535. The effective maximum length of a VARCHAR is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used. For example, utf8 characters can require up to three bytes per character, so a VARCHAR column that uses the utf8 character set can be declared to be a maximum of 21,844 characters.
MariaDB stores VARCHAR values as a one-byte or two-byte length prefix plus data. The length prefix indicates the number of bytes in the value. A VARCHAR column uses one length byte if values require no more than 255 bytes, two length bytes if values may require more than 255 bytes.
Note: MariaDB 5.1 and later follow the standard SQL specification, and do not remove trailing spaces from VARCHAR values.
VARCHAR(0) columns can contain 2 values: an empty string or NULL. Such columns cannot be part of an index. The CONNECT storage engine does not support VARCHAR(0).
VARCHAR is shorthand for CHARACTER VARYING. NATIONAL VARCHAR is the standard SQL way to define that a VARCHAR column should use some predefined character set. MariaDB uses utf8 as this predefined character set, as does MySQL 4.1 and up. NVARCHAR is shorthand for NATIONAL VARCHAR.
The following are equivalent:
VARCHAR(30) CHARACTER SET utf8 NATIONAL VARCHAR(30) NVARCHAR(30) NCHAR VARCHAR(30) NATIONAL CHARACTER VARYING(30) NATIONAL CHAR VARYING(30)