sql 字符串处理函数(1/5)

下面列出了大家常用的sql 字符串处理函数，好了开始看

绝对值
  sql:select abs(-1) value
  o:select abs(-1) value from dual
  2.取整(大)
  s:select ceiling(-1.001) value
  o:select ceil(-1.001) value from dual
  3.取整（小）
  s:select floor(-1.001) value
  o:select floor(-1.001) value from dual
  4.取整（截取）
  s:select cast(-1.002 as int) value
  o:select trunc(-1.002) value from dual
  5.四舍五入
  s:select round(1.23456,4) value 1.23460
  o:select round(1.23456,4) value from dual 1.2346
  6.e为底的幂
  s:select exp(1) value 2.7182818284590451
  o:select exp(1) value from dual 2.71828182
  7.取e为底的对数
  s:select log(2.7182818284590451) value 1
  o:select ln(2.7182818284590451) value from dual; 1
  8.取10为底对数
  s:select log10(10) value 1
  o:select log(10,10) value from dual; 1
  9.取平方
  s:select square(4) value 16
  o:select power(4,2) value from dual 16
  10.取平方根
  s:select sqrt(4) value 2
  o:select sqrt(4) value from dual 2
  11.求任意数为底的幂
  s:select power(3,4) value 81
  o:select power(3,4) value from dual 81
  12.取随机数
  s:select rand() value
  o:select sys.dbms_random.value(0,1) value from dual;
  13.取符号
  s:select sign(-8) value -1
  o:select sign(-8) value from dual -1
  ----------数学函数