Space
char (m): m bytes, 0 = <m <= 255
VARCHAR (m): L + byte. 1, 0 = <m <= 65535 , L is the actual length of
text: L + 2 words section, L <216
char: fixed length, lack of space if, English (ASCII) character occupies one byte, a character occupies 2 bytes
varchar: not fill the spaces, each English (ASCII) characters and occupies 2 bytes
text : The maximum length is 65535 (2 ^ 6-1) characters
MEDIUMTEXT: maximum length (2 ^ 24-1) 16777215 characters
LONGTEXT: maximum length (2 ^ 32-1) 4,294,967,295 characters