PI()

函数说明

PI() 返回数学常量 π (pi)。

函数语法

1. > PI()

示例

1. drop table if exists t1;
2. create table t1(a int,b float);
3. insert into t1 values(0,0),(-15,-20),(-22,-12.5);
4. insert into t1 values(0,360),(30,390),(90,450),(180,270),(180,180);

6. mysql> select acos(a*pi()/180) as acosa,acos(b*pi()/180) acosb from t1;
7. +--------------------+--------------------+
8. | acosa              | acosb              |
9. +--------------------+--------------------+
10. | 1.5707963267948966 | 1.5707963267948966 |
11. | 1.8356824738191324 |  1.927370391646567 |
12. | 1.9648910192076245 | 1.7907312931992256 |
13. | 1.5707963267948966 |               NULL |
14. | 1.0197267436954502 |               NULL |
15. |               NULL |               NULL |
16. |               NULL |               NULL |
17. |               NULL |               NULL |
18. +--------------------+--------------------+
19. 8 rows in set (0.01 sec)

21. mysql> select acos(a*pi()/180)*acos(b*pi()/180) as acosab,acos(acos(a*pi()/180)) as c from t1;
22. +--------------------+------+
23. | acosab             | c    |
24. +--------------------+------+
25. | 2.4674011002723395 | NULL |
26. | 3.5380400485035204 | NULL |
27. |  3.518591835821214 | NULL |
28. |               NULL | NULL |
29. |               NULL | NULL |
30. |               NULL | NULL |
31. |               NULL | NULL |
32. |               NULL | NULL |
33. +--------------------+------+
34. 8 rows in set (0.01 sec)