2007-10-04 14:18:15

1.絕對(duì)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為底的冪

S:select? ?Exp(1)? ?value? ?2.7182818284590451

O:select? ?Exp(1)? ?value? ?from? ?dual? ?2.71828182

7.取e為底的對(duì)數(shù)

S:select? ?log(2.7182818284590451)? ?value? ?1

O:select? ?ln(2.7182818284590451)? ?value? ?from? ?dual;? ?1

8.取10為底對(duì)數(shù)

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.求任意數(shù)為底的冪

S:select? ?power(3,4)? ?value? ?81

O:select? ?power(3,4)? ?value? ?from? ?dual? ?81

12.取隨機(jī)數(shù)

S:select? ?rand()? ?value

O:select? ?sys.dbms_random.value(0,1)? ?value? ?from? ?dual;

13.取符號(hào)

S:select? ?sign(-8)? ?value? ?-1

O:select? ?sign(-8)? ?value? ?from? ?dual? ?-1

----------數(shù)學(xué)函數(shù)

14.圓周率

S:SELECT? ?PI()? ?value? ?3.1415926535897931

O:不知道

15.sin,cos,tan? ?參數(shù)都以弧度為單位

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

16.Asin,Acos,Atan,Atan2? ?返回弧度

17.弧度角度互換(SQLServer，Oracle不知道)

DEGREES：弧度-〉角度

RADIANS：角度-〉弧度

---------數(shù)值間比較

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.如何處理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

--------數(shù)值間比較

21.求字符序號(hào)

S:select? ?ascii('a')? ?value

O:select? ?ascii('a')? ?value? ?from? ?dual

22.從序號(hào)求字符

S:select? ?char(97)? ?value

O:select? ?chr(97)? ?value? ?from? ?dual

23.連接

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

23.模糊子串的位置? ?--返回2,參數(shù)去掉中間%則返回7

S:select? ?patindex('%d%q%','sdsfasdqe')? ?value

Oracle沒發(fā)現(xiàn)，但是instr可以通過第四霾問刂瞥魷執(zhí)問?BR>　　select? ?INSTR('sdsfasdqe','sd',1,2)? ?value? ?from? ?dual? ?返回6

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.子串全部替換

S:沒發(fā)現(xiàn)

O:select? ?Translate('fasdbfasegas','fa','我'? ?)? ?value? ?from? ?dual

27.長度

S:len,datalength

O:length

28.大小寫轉(zhuǎn)換? ?lower,upper

29.單詞首字母大寫

S:沒發(fā)現(xiàn)

O:select? ?INITCAP('abcd? ?dsaf? ?df')? ?value? ?from? ?dual

30.左補(bǔ)空格(LPAD的第一個(gè)參數(shù)為空格則同space函數(shù))

S:select? ?space(10)+'abcd'? ?value

O:select? ?LPAD('abcd',14)? ?value? ?from? ?dual

31.右補(bǔ)空格(RPAD的第一個(gè)參數(shù)為空格則同space函數(shù))

S:select? ?'abcd'+space(10)? ?value

O:select? ?RPAD('abcd',14)? ?value? ?from? ?dual

32.刪除空格

S:ltrim,rtrim

O:ltrim,rtrim,trim

33.? ?重復(fù)字符串

S:select? ?REPLICATE('abcd',2)? ?value

O:沒發(fā)現(xiàn)

34.發(fā)音相似性比較(這兩個(gè)單詞返回值一樣，發(fā)音相同)

S:SELECT? ?SOUNDEX? ?('Smith'),? ?SOUNDEX? ?('Smythe')

O:SELECT? ?SOUNDEX? ?('Smith'),? ?SOUNDEX? ?('Smythe')? ?from? ?dual

SQLServer中用SELECT? ?DIFFERENCE('Smithers',? ?'Smythers')? ?比較soundex的差

返回0-4，4為同音，1最高

--------------日期函數(shù)

35.系統(tǒng)時(shí)間

S:select? ?getdate()? ?value

O:select? ?sysdate? ?value? ?from? ?dual

36.前后幾日

直接與整數(shù)相加減

37.求日期

S:select? ?convert(char(10),getdate(),20)? ?value

O:select? ?trunc(sysdate)? ?value? ?from? ?dual

select? ?to_char(sysdate,'yyyy-mm-dd')? ?value? ?from? ?dual

38.求時(shí)間

S:select? ?convert(char(8),getdate(),108)? ?value

O:select? ?to_char(sysdate,'hh24:mm:ss')? ?value? ?from? ?dual

39.取日期時(shí)間的其他部分

S:DATEPART? ?和? ?DATENAME? ?函數(shù)? ?(第一個(gè)參數(shù)決定)

O:to_char函數(shù)? ?第二個(gè)參數(shù)決定

參數(shù)---------------------------------下表需要補(bǔ)充

year? ?yy,? ?yyyy

quarter? ?qq,? ?q? ?(季度)

month? ?mm,? ?m? ?(m? ?O無效)

dayofyear? ?dy,? ?y? ?(O表星期)

day? ?dd,? ?d? ?(d? ?O無效)

week? ?wk,? ?ww? ?(wk? ?O無效)

weekday? ?dw? ?(O不清楚)

Hour? ?hh,hh12,hh24? ?(hh12,hh24? ?S無效)

minute? ?mi,? ?n? ?(n? ?O無效)

second? ?ss,? ?s? ?(s? ?O無效)

millisecond? ?ms? ?(O無效)

----------------------------------------------

40.當(dāng)月最后一天

S:不知道

O:select? ?LAST_DAY(sysdate)? ?value? ?from? ?dual

41.本星期的某一天(比如星期日)

S:不知道

O:SELECT? ?Next_day(sysdate,7)? ?vaule? ?FROM? ?DUAL;

42.字符串轉(zhuǎn)時(shí)間

S:可以直接轉(zhuǎn)或者select? ?cast('2004-09-08'as? ?datetime)? ?value

O:SELECT? ?To_date('2004-01-05? ?22:09:38','yyyy-mm-dd? ?hh24-mi-ss')? ?vaule? ?FROM? ?DUAL;

43.求兩日期某一部分的差(比如秒)

S:select? ?datediff(ss,getdate(),getdate()+12.3)? ?value

O:直接用兩個(gè)日期相減(比如d1-d2=12.3)

SELECT? ?(d1-d2)*24*60*60? ?vaule? ?FROM? ?DUAL;

44.根據(jù)差值求新的日期(比如分鐘)

S:select? ?dateadd(mi,8,getdate())? ?value

O:SELECT? ?sysdate+8/60/24? ?vaule? ?FROM? ?DUAL;

45.求不同時(shí)區(qū)時(shí)間

S:不知道

O:SELECT? ?New_time(sysdate,'ydt','gmt'? ?)? ?vaule? ?FROM? ?DUAL;

-----時(shí)區(qū)參數(shù),北京在東8區(qū)應(yīng)該是Ydt-------

AST? ?ADT? ?大西洋標(biāo)準(zhǔn)時(shí)間

BST? ?BDT? ?白令海標(biāo)準(zhǔn)時(shí)間

CST? ?CDT? ?中部標(biāo)準(zhǔn)時(shí)間

EST? ?EDT? ?東部標(biāo)準(zhǔn)時(shí)間

GMT? ?格林尼治標(biāo)準(zhǔn)時(shí)間

HST? ?HDT? ?阿拉斯加—夏威夷標(biāo)準(zhǔn)時(shí)間

MST? ?MDT? ?山區(qū)標(biāo)準(zhǔn)時(shí)間

NST? ?紐芬蘭標(biāo)準(zhǔn)時(shí)間

PST? ?PDT? ?太平洋標(biāo)準(zhǔn)時(shí)間

YST? ?YDT? ?YUKON標(biāo)準(zhǔn)時(shí)間

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