要查找字符串的ASCII值，可以使用MySQL内置函数ASCII()。

以下是一个示例查询，展示如何使用ASCII()函数查找字符串"Hello World!"的每个字符的ASCII值：

SELECT ASCII('H') AS H,

ASCII('e') AS e,

ASCII('l') AS l,

ASCII('l') AS l2,

ASCII('o') AS o,

ASCII(' ') AS space,

ASCII('W') AS W,

ASCII('o') AS o2,

ASCII('r') AS r,

ASCII('l') AS l3,

ASCII('d') AS d,

ASCII('!') AS exclamation;

执行该查询将返回以下结果：

+------+------+------+------+------+------+------+------+------+------+------+-------------+

| H | e | l | l2 | o | space | W | o2 | r | l3 | d | exclamation |

+------+------+------+------+------+------+------+------+------+------+------+-------------+

| 72 | 101 | 108 | 108 | 111 | 32 | 87 | 111 | 114 | 108 | 100 | 33 |

+------+------+------+------+------+------+------+------+------+------+------+-------------+

结果显示了字符串中每个字符对应的ASCII值。注意，为了区分相同的字符，我们在查询中对重复的字符进行了重新命名（例如，"l"被分别命名为"l"、"l2"和"l3"）。

希望这对你有帮助！