oracle數(shù)據(jù)類型及存儲(chǔ)方式

1、acleacle數(shù)據(jù)類型及存儲(chǔ)方式數(shù)據(jù)類型及存儲(chǔ)方式(acle小組學(xué)習(xí)筆記)袁光東概述............................................................................................................................................1第一部份字符類型............................

2、......................................................................................11.1..........................................................................................................................11.2var2

3、...................................................................................................................31.3byte和................................................................................................

4、............41.4還是var.................................................................................................71.5N和NVAR2....................................................................................81.6RAW

5、.....................................................................................................................10第二部分?jǐn)?shù)值類型.............................................................................................

6、...................122.1number.................................................................................................................122.2小數(shù)位在哪里？.................................................................

7、....................................142.3number的精度和小數(shù)位........................................................................................152.4binary_float和binary_double...............................................

8、..............................192.5acle在語法上還支持的數(shù)值數(shù)據(jù)類型..............................................................21第三部分日期時(shí)間類型.............................................................................................

9、...........213.1DATE....................................................................................................................213.2向Date類型增加或減時(shí)間..................................................................

10、.................233.3TIMESTAMP..........................................................................................................263.4TIMESTAMPWITHTIMEZONE.........................................................

11、.............283.5TIMESTAMPWITHLOCALTIMEZONE..........................................................293.6INTERVAL.........................................................................................................

12、..30第四部分LOB類型.........................................................................................................324.1LOB類型............................................................................................

13、.................324.2BFILE..................................................................................................................37第五部分LONG類型...................................................................

14、............................................37第六部分ROWID................................................................................................................38概述概述通過實(shí)例，全面而深入的分析alce的基本數(shù)據(jù)類型及它們的存儲(chǔ)方式。以ACLE10G為基礎(chǔ)，介紹

15、alce10g引入的新的數(shù)據(jù)類型。讓你對(duì)acle數(shù)據(jù)類型有一個(gè)全新的認(rèn)識(shí)。揭示一些不為人知的秘密和被忽略的盲點(diǎn)。從實(shí)用和優(yōu)化的角度出發(fā)，討論每種數(shù)據(jù)類型的特點(diǎn)。從這里開始acle之旅！aaTyp=96Len=10:97973232323232323232aaaTyp=96Len=10:97979732323232323232aaaaTyp=96Len=10:97979797323232323232aaaaaaaaaaTyp=96Len=

16、10:97979797979797979797注意：Typ=96表示數(shù)據(jù)類型的ID。acle為每一種數(shù)據(jù)類型都進(jìn)行了編號(hào)。說明類型的編號(hào)是96.Len=10表示所在的內(nèi)部存儲(chǔ)的長(zhǎng)度(用字節(jié)表示)。雖然第一例只存了一個(gè)字符’a’，但是它還是占用了10個(gè)字節(jié)的空間。97323232323232323232表示內(nèi)部存儲(chǔ)方式?？梢奱cle的內(nèi)部存儲(chǔ)是以ii碼進(jìn)行存儲(chǔ)的。97正好是字符a的II碼?？梢允褂胏hr函數(shù)把II碼轉(zhuǎn)成字符。SQLchr(

17、97)fromdualCHR(97)a要想知道一個(gè)字符的II碼，可以使用函數(shù)iiSQLii(a)fromdualII(A)9732正好是空格的ii碼值。類型是定長(zhǎng)類型。它總會(huì)以空格來填充以達(dá)到一個(gè)固定寬度。使用類型會(huì)浪費(fèi)存儲(chǔ)空間。acle的數(shù)據(jù)類型的長(zhǎng)度單位是字節(jié)。SQLdump(漢)fromdualDUMP(漢)Typ=96Len=2:186186可見一個(gè)漢字在acle中是占用了兩個(gè)字節(jié)的。英文字母或符號(hào)只占用一個(gè)字節(jié)。(10)最多可