怎样区别oracle与sql的常用函数(2)

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

    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