MySQL BIT_LENGTH() 函数是否是多字节安全的？
Just like LENGTH() function, MySQL BIT_LENGTH() function is not a multi-byte safe function. As we know that the difference of the result between multi-byte safe functions, like CHAR_LENGTH() or CHARACTER_LENGTH(), and BIT_LENGTH() function especially relevant for Unicode, in which most of the characters are encoded in two bytes or relevant for UTF-8 where the number of bytes varies. It is demonstrated in the example below −
Example
mysql> Select BIT_LENGTH('tutorialspoint'); +------------------------------+ | BIT_LENGTH('tutorialspoint') | +------------------------------+ | 112 | +------------------------------+ 1 row in set (0.00 sec)登录后复制
mysql> SET @A = CONVERT('tutorialspoint' USING ucs2); Query OK, 0 rows affected (0.02 sec)登录后复制
mysql> Select BIT_LENGTH(@A); +----------------+ | BIT_LENGTH(@A) | +----------------+ | 224 | +----------------+ 1 row in set (0.00 sec)登录后复制
