How to set varchar length in mysql _ MySQL

In mysql, if varchar length is set to 50 in one item, then of course 50 in English, then in Chinese, UTF-8 occupies three bytes in Chinese, can this varchar (50) only store 16 Chinese characters? Mysql varchar (50) stores 50 files in both Chinese and English.
In MySQL5, the varchar field type is described as follows: varchar (m) variable-length string. M indicates the maximum column length. M ranges from 0 to 65,535. (The maximum actual length of a VARCHAR is determined by the maximum row size and the character set used. The maximum valid length is 65,532 bytes ). Why is this change? I really feel that the MySQL manual is too unfriendly, because you need to read it carefully before you can find this description: MySQL 5.1 complies with standard SQL specifications, the trailing space of the VARCHAR value is not deleted. When VARCHAR is saved, it uses a prefix of one or two bytes plus data. If the length declared by the VARCHAR column is greater than 255, the length prefix is two bytes. Well, it seems I understand a little bit. However, when the length is greater than 255, the prefix of two bytes is used. The primary subtraction question is: 65535-2 = 65533. I don't know how these Daniel calculate it. do you still have questions? Note: I tested UTF8 encoding. The maximum length of varchar is 21854 bytes. In mysql 5.0.45, the database code utf8 is tested: varchar is defined as 21785 at most. That is to say, only 21785 letters, numbers, and Chinese characters are allowed. Suppose: varchar has a maximum byte value of 65535, and utf8 is encoded into three characters: 65535/3 = 21785.