sql和oracle的区别|怎样区别oracle与sql的常用函数(2)

  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 ----------三角函数相关

  14.圆周率S:SELECT PI() value 3.1415926535897931

  O:不知道

  15.sin,cos,tan 参数都以弧度为单位

  例如：select sin(PI()/2) value得到1（SQLServer）

  16.Asin,Acos,Atan,Atan2 返回弧度

  17.弧度角度互换(SQLServer，Oracle不知道)

  DEGREES：弧度-〉角度

  RADIANS：角度-〉弧度

  ---------数值间比较

  18. 求集合最大值

  S:select max(value) value from

  (select 1 value

  union

  select -2 value

  union

  select 4 value

  union

  select 3 value)a

  O:select greatest(1,-2,4,3) value from dual

  19. 求集合最小值

  S:select min(value) value from

  (select 1 value

  union

  select -2 value

  union

  select 4 value

  union

  select 3 value)a

  O:select least(1,-2,4,3) value from dual

  20.如何处理null值(F2中的null以10代替) S:select F1,IsNull(F2,10) value from Tbl O:select F1,nvl(F2,10) value from Tbl

  --------字符串函数

  21.求字符序号

  S:select ascii("a") value

  O:select ascii("a") value from dual

  22.从序号求字符

  S:select char(97) value

  O:select chr(97) value from dual

  23.连接

  S:select "11"+"22"+"33" value

  O:select CONCAT("11","22")||33 value from dual

  23.子串位置 --返回3 S:select CHARINDEX("s","sdsq",2) value O:select INSTR("sdsq","s",2) value from dual

sql和oracle的区别|怎样区别oracle与sql的常用函数(2)

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