In MySQL-4.x and earlier, NCHAR and CHAR were synonymous. ANSI defines NCHAR or NATIONAL CHAR as a way to define that a CHAR column should use some predefined character set. MySQL uses utf8 as that predefined character set. For example, these column type declarations are equivalent:
CHAR(10) CHARACTER SET utf8 NATIONAL CHARACTER(10) NCHAR(10)
As are these:
VARCHAR(10) CHARACTER SET utf8 NATIONAL VARCHAR(10) NCHAR VARCHAR(10) NATIONAL CHARACTER VARYING(10) NATIONAL CHAR VARYING(10)
You can use N'literal' to create a string in national character set.
These two statements are equivalent:
SELECT N'some text'; SELECT _utf8'some text';