日期：2015/6/28来源: IT猫扑网
---------数学函数 ---------------
1.绝对值
S: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
----------三角函数相关----------------------
14.圆周率
S:SELECT PI() value 3.1415926535897931
O:SELECT ACOS(-1)from dual 3.1415926535897932384626433832795028842
15.sin,cos,tan 参数都以弧度为单位
S:SELECT sin() value
O:SELECT sin() value from dual
16.Asin,Acos,Atan,Atan2 参数都以弧度为单位
S:SELECT Asin() value
O:SELECT Asin() value from dual
17.弧度角度互换
S:DEGREES：弧度-〉角度 RADIANS：角度-〉弧度
O:没有提供内建的弧度和角度的转换函数。
---------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
S:select CHARINDEX('s','sdsq',2) value
CHARINDEX(源字符串, 目标字符串, 起始位置)
O:select INSTR('sdsq','s',2) value from dual
INSTR(源字符串, 目标字符串, 起始位置, 匹配序号)
23.模糊子串的位置 --返回2,参数去掉中间%则返回7
S:select patindex('%d%q%','sdsfasdqe') value
PATINDEX(%[a,z,0-9]%[a,z,0-9]%[a,z,0-9]%,xyzabc123)
PATINDEX(源字符串, 目标字符串)
O:oracle无
24.求子串
S:select substring('abcd',2,2) value
O:select substr('abcd',2,2) value from dual
25.子串代替 返回aijklmnef
S:SELECT STUFF('abcdef', 2, 3, 'ijklmn') value
O:SELECT Replace('abcdef', 'bcd', 'ijklmn') value from dual
26.子串全部替换
S:Replace
O:select translate('fasdbfasegas','fa','FA' ) value from dual FAsdbFAsegAs
27.长度
S:len,datalength
O:length
28.大小写转换 lower,upper
29.单词首字母大写
S:无
O:select INITCAP('abcd dsaf df') value from dual Abcd Dsaf Df
30.左补空格（LPAD的第一个参数为空格则同space函数）
S:select space(10)+'abcd' value
O:select LPAD('abcd',14) value from dual
LPAD(字符串,补齐空格后字符串的总长度)
31.右补空格（RPAD的第一个参数为空格则同space函数）
S:select 'abcd'+space(10) value
O:select RPAD('abcd',14) value from dual
RPAD(字符串,补齐空格后字符串的总长度)
32.删除空格
S:ltrim,rtrim,replace(字符串,' ','')
O:ltrim,rtrim,trim
33.字符串重复N次
S:select REPLICATE('abcd',2) value
O:没发现
34.发音相似性比较(这两个单词返回值一样，发音相同)
S:SELECT SOUNDEX ('Smith'), SOUNDEX ('Smythe')
O:SELECT SOUNDEX ('Smith'), SOUNDEX ('Smythe') from dual
SQLServer中用SELECT DIFFERENCE('Sm
相关文章
相关下载
网友评论