lect ASIN('foo');
-> 0.000000
ATAN(N)
返回N的反正切值
mysql> select ATAN(2);
-> 1.107149
mysql> select ATAN(-2);
-> -1.107149
ATAN2(X,Y)
返回2个变量X和Y的反正切(类似Y/X的反正切,符号决定象限)
mysql> select ATAN(-2,2);
-> -0.785398
mysql> select ATAN(PI(),0);
-> 1.570796
COT(N)
返回X的余切
mysql> select COT(12);
-> -1.57267341
mysql> select COT(0);
-> NULL
RAND()
RAND(N)
返回在范围0到1.0内的随机浮点值(可以使用数字N作为初始值)
mysql> select RAND();
-> 0.5925
mysql> select RAND(20);
-> 0.1811
mysql> select RAND(20);
-> 0.1811
mysql> select RAND();
-> 0.2079
mysql> select RAND();
-> 0.7888
DEGREES(N)
把N从弧度变换为角度并返回
mysql> select DEGREES(PI());
-> 180.000000
RADIANS(N)
把N从角度变换为弧度并返回
mysql> select RADIANS(90);
-> 1.570796
TRUNCATE(N,D)
保留数字N的D位小数并返回
mysql> select TRUNCATE(1.223,1);
-> 1.2
mysql> select TRUNCATE(1.999,1);
-> 1.9
mysql> select TRUNCATE(1.999,0);
-> 1
LEAST(X,Y,...)
返回最小值(如果返回值被用在整数(实数或大小敏感字串)上下文或所有参数都是整数(实数或大小敏感字串)则他们作为整数(实数或大小敏感字串)比较,否则按忽略大小写的字符串被比较)
mysql> select LEAST(2,0);
-> 0
mysql> select LEAST(34.0,3.0,5.0,767.0);
-> 3.0
mysql> select LEAST("B","A","C");
-> "A"
GREATEST(X,Y,...)
返回最大值(其余同LEAST())
mysql> select GREATEST(2,0);
-> 2
mysql> select GREATEST(34.0,3.0,5.0,767.0);
-> 767.0
mysql> select GREATEST("B","A","C");
-> "C"
时期时间函数
DAYOFWEEK(date)
返回日期date是星期几(1=星期天,2=星期一,……7=星期六,ODBC标准)
mysql> select DAYOFWEEK('1998-02-03');
-> 3
WEEKDAY(date)
返回日期date是星期几(0=星期一,1=星期二,……6= 星期天)。
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