mysql> select cos(PI()/3); +--------------------+ | cos(PI()/3) | +--------------------+ | 0.5000000000000001 | +--------------------+ 1 row in set (0.00 sec)
//获取pi
mysql> select pi(); +----------+ | pi() | +----------+ | 3.141593 | +----------+ 1 row in set (0.00 sec)