DB2中所謂的數(shù)據(jù)移動,包括:
1. 數(shù)據(jù)的導(dǎo)入(Import)
2. 數(shù)據(jù)的導(dǎo)出(Export)
 3. 數(shù)據(jù)的裝入(Load)。
導(dǎo)入和裝入都是利用DB2的相關(guān)命令把某種格式的文件中的數(shù)據(jù)保存到數(shù)據(jù)庫中的表中;
導(dǎo)出是指把DB2數(shù)據(jù)庫的表中的數(shù)據(jù)保存到某種格式的文件當(dāng)中去。

首先介紹一下文件的格式,用于DB2數(shù)據(jù)移動的文件格式有四種:

1. ASC——非定界ASCII文件,是一個ASCII字符流。數(shù)據(jù)流中的行由行定界符分隔,而行中的每一列則通過起始和結(jié)束位置來定義。例如:

10 Head Office 160 Corporate New York

15 New England 50 Eastern Boston

20 Mid Atlantic 10 Eastern Washington

38 South Atlantic 30 Eastern Atlanta

42 Great Lakes 100 Midwest Chicago

2. DEL——定界ASCII文件,也是一個ASCII字符流。數(shù)據(jù)流中的行由行定界符分隔,行中的列值由列定界符分隔。文件類型修飾符可用于修改這些定界符的默認(rèn)值。例如:

10,"Head Office",160,"Corporate","New York"

15,"New England",50,"Eastern","Boston"

20,"Mid Atlantic",10,"Eastern","Washington"

38,"South Atlantic",30,"Eastern","Atlanta"

42,"Great Lakes",100,"Midwest","Chicago"

51,"Plains",140,"Midwest","Dallas"

66,"Pacific",270,"Western","San Francisco"

84,"Mountain",290,"Western","Denver"

3. WSF——(work sheet format)為工作表格式,用于與Lotus系列的軟件進(jìn)行數(shù)據(jù)交換。
 
4. PC/IXF——是集成交換格式(Integration Exchange Format,IXF)數(shù)據(jù)交換體系結(jié)構(gòu)的改編版本,由一些列可變長度的記錄構(gòu)成,包括頭記錄、表記錄、表中每列的列描述符記錄以及表中每行的一條或多條數(shù)據(jù)記錄。PC/IXF 文件記錄由包含了字符數(shù)據(jù)的字段組成。

數(shù)據(jù)的導(dǎo)出(Export)
例一:把Org表中的所有數(shù)據(jù)導(dǎo)出到文件C:\ORG.TXT中。

Export to c:\org.txt of del select * from org

其中,of del表示導(dǎo)出到的文件的類型,在本例中導(dǎo)出到一個非定界文本文件中;后面的select * from org是一個SQL語句,該語句查詢出來的結(jié)果就是要導(dǎo)出的數(shù)據(jù)。

例二:改變del格式文件的格式控制符

export to c:\staff.txt of del modified by coldel$ chardel'' decplusblank select * from staff

在該例中,modified子句用于控制各種符號,coldel表示字段之間的間隔符,默認(rèn)情況為逗號,現(xiàn)在改為$號;chardel表示字符串字段用什么符號引用,默認(rèn)情況下為一對雙引號括起來,現(xiàn)在改為用一對單引號括起來;decplusblank表示對于十進(jìn)制數(shù)據(jù)類型,用空格代替最前面的加號,因為默認(rèn)情況下會在十進(jìn)制數(shù)據(jù)前面加上正負(fù)號的。 www.3s8.cn

例三:以ASC格式將數(shù)據(jù)導(dǎo)出到文件

Export命令是不支持ASC格式文件的,所以如果想導(dǎo)出ASC這樣規(guī)整的格式,需要程序員自己進(jìn)行轉(zhuǎn)換操作,思路是將各種數(shù)據(jù)類型都轉(zhuǎn)換成定長字符串,然后把各個要導(dǎo)出的字段合并成為一個字段。

例如創(chuàng)建如下結(jié)構(gòu)的表n:

create table n(a int,b date,c time,d varchar(5),e char(4),f double)

然后插入兩條數(shù)據(jù):

insert into n values(15,'2004-10-21','23:12:23','abc','hh',35.2)

insert into n values(5,'2004-1-21','3:12:23','bc','hhh',35.672)

要想把這兩條數(shù)據(jù)以規(guī)整的格式導(dǎo)出到文件中,進(jìn)行如下操作:

export to c:\test.txt of del select char(a) || char(b) || char(c) || char(d,5) || e || char(f) as tmp from n

這樣導(dǎo)出的結(jié)果與ASC格式的文件非常類似,只是每一行的前后多出了一對雙引號,對此我們可以使用文本工具(如寫字板、記事本等)把雙引號刪除掉,也可以置之不理,在以后導(dǎo)入的時候直接控制格式(忽略雙引號)

在文件中的格式為:

"15 2004-10-2123.12.23abc hh 3.52E1 "

"5 2004-01-2103.12.23bc hhh 3.5672E1 "

例四:大數(shù)據(jù)的導(dǎo)出

export to d:\myfile.del of del lobs to d:\lob\ lobfile lobs modified by lobsinfile select * from emp_photo

該命令把emp_photo表的數(shù)據(jù)導(dǎo)出到d:\myfile.del文件中,其結(jié)果為:

<pre>

"000130","bitmap","lobs.001.0.43690/"

"000130","gif","lobs.001.43690.29540/"

"000130","xwd","lobs.001.73230.45800/"

"000140","bitmap","lobs.001.119030.71798/"

"000140","gif","lobs.001.190828.29143/"

"000140","xwd","lobs.001.219971.73908/"

"000150","bitmap","lobs.001.293879.73438/"

"000150","gif","lobs.001.367317.39795/"