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)