ASIN(X)

ASIN()函數返回X的反正弦，X的值必須在-1至1範圍內，返回NULL。

mysql> SELECT ASIN(1);
+---------------------------------------------------------+
| ASIN(1)                                                 |
+---------------------------------------------------------+
| 1.5707963267949                                         |
+---------------------------------------------------------+
1 row in set (0.00 sec)