ASCII(str)
返回最左边的字符的字符串str的数值。如果str是空字符串,返回0。如果str为NULL,返回NULL。 ASCII()是从0到255的数值的字符。
SQL> SELECT ASCII('2'); +---------------------------------------------------------+ | ASCII('2') | +---------------------------------------------------------+ | 50 | +---------------------------------------------------------+ 1 row in set (0.00 sec) SQL> SELECT ASCII('dx'); +---------------------------------------------------------+ | ASCII('dx') | +---------------------------------------------------------+ | 100 | +---------------------------------------------------------+ 1 row in set (0.00 sec)