外部表：
这些表并不存储在数据库本身中，而是放在数据库之外，即放在平常的操作系统文件中。在Oracle9i
及以上版本中，利用外部表可以查询数据库之外的一个文件，就好像这个文件也是数据库中平常的表一样。外部表对于向数据
库加载数据最有用（外部表是非常强大的数据加载工具）
- 创建的语法类似于： "CREATE TABLE ... ORGANIZATION EXTERNAL"
- 数据在数据库的外部组织，是操作系统文件。
- 操作系统文件在数据库中的标志是通过一个逻辑目录来映射的。
- 数据是只读的。（外部表相当于一个临时的只读的虚表）
- 不可以在上面运行任何 DML 操作，不可以创建索引。
- 可以查询操作和连接。可以并行操作。
例子：
1、有以下文件demo.txt：
Txt代码
- 20100830000000,0830,10086,01,0551,40,2,11,100,20100830000005,11,
- 20100830000000,0830,10086,01,0551,40,2,11,100,20100830000008,11,
- 20100830000000,0830,10086,08,0558,32,3,11,100,20100830000009,11,
- 20100830000000,0830,10086,17,0567,32,3,11,100,20100830000313,11,
- 20100830000001,0830,10086,01,0551,32,3,1911,100,201008300000,11,
- 20100830000001,0830,10086,01,0551,32,3,11,100,20100830000011,11,
- 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000013,11,
- 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000015,11,
- 20100830000001,0830,10086,03,0553,40,2,11,100,20100830000021,11,
- 20100830000001,0830,10086,03,0553,40,2,10,80,20100830000145,11,
- 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000306,11,
- 20100830000001,0830,10086,11,0561,32,3,11,100,20100830000311,11,
- 20100830000001,0830,10086,07,0557,32,3,11,100,20100830000313,11,
- 20100830000001,0830,10086,14,0564,52,1,12,100,20100830000328,12,
- 20100830000002,0830,10086,10,0550,40,2,11,100,20100830000006,11,
- 20100830000002,0830,10086,14,0564,40,2,11,100,20100830000007,11,
- 20100830000002,0830,10086,10,0550,40,2,11,100,20100830000011,11,
- 20100830000002,0830,10086,01,0551,40,2,10,80,20100830000017,10,
20100830000000,0830,10086,01,0551,40,2,11,100,20100830000005,11, 20100830000000,0830,10086,01,0551,40,2,11,100,20100830000008,11, 20100830000000,0830,10086,08,0558,32,3,11,100,20100830000009,11, 20100830000000,0830,10086,17,0567,32,3,11,100,20100830000313,11, 20100830000001,0830,10086,01,0551,32,3,1911,100,201008300000,11, 20100830000001,0830,10086,01,0551,32,3,11,100,20100830000011,11, 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000013,11, 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000015,11, 20100830000001,0830,10086,03,0553,40,2,11,100,20100830000021,11, 20100830000001,0830,10086,03,0553,40,2,10,80,20100830000145,11, 20100830000001,0830,10086,08,0558,32,3,11,100,20100830000306,11, 20100830000001,0830,10086,11,0561,32,3,11,100,20100830000311,11, 20100830000001,0830,10086,07,0557,32,3,11,100,20100830000313,11, 20100830000001,0830,10086,14,0564,52,1,12,100,20100830000328,12, 20100830000002,0830,10086,10,0550,40,2,11,100,20100830000006,11, 20100830000002,0830,10086,14,0564,40,2,11,100,20100830000007,11, 20100830000002,0830,10086,10,0550,40,2,11,100,20100830000011,11, 20100830000002,0830,10086,01,0551,40,2,10,80,20100830000017,10,
2、创建目录，并赋予权限
Sql代码
- SQL> CREATE DIRECTORY testdir AS 'd:\temp\';
- Directory created
- SQL> GRANT ALL ON DIRECTORY testdir TO scott;
- Grant succeeded
SQL> CREATE DIRECTORY testdir AS 'd:\temp\'; Directory created SQL> GRANT ALL ON DIRECTORY testdir TO scott; Grant succeeded
注意：接着把student.txt文件拷贝到d:\temp下面
3、创建外部表
Sql代码
- CREATE TABLE demo_ext(
- LogDate VARCHAR2(20),
- PartID CHAR(4),
- CalleeNo VARCHAR2(20),
- CityID VARCHAR2(10),
- CityCode VARCHAR2(5),
- UserGrade NUMBER(4),
- UserType NUMBER(4),
- OperateTrace VARCHAR2(30),
- OperateResult NUMBER(4),
- PressDate VARCHAR2(20),
- KeyTrace VARCHAR2(10),
- ExitDate VARCHAR2(20)
- )
- ORGANIZATION EXTERNAL(
- TYPE ORACLE_LOADER
- DEFAULT DIRECTORY testdir
- ACCESS PARAMETERS (
- RECORDS DELIMITED BY NEWLINE
- BADFILE 'bad.txt'
- LOGFILE 'log.txt'
- READSIZE 10485760
- FIELDS TERMINATED BY ','
- LDRTRIM
- MISSING FIELD VALUES ARE NULL
- REJECT ROWS WITH ALL NULL FIELDS
- (LogDate,PartID,CalleeNo,CityID,CityCode,UserGrade,UserType,OperateTrace,OperateResult,PressDate,KeyTrace,ExitDate)
- )
- LOCATION('demo.txt')
- )reject limit unlimited
- /
CREATE TABLE demo_ext(
LogDate VARCHAR2(20),
PartID CHAR(4),
CalleeNo VARCHAR2(20),
CityID VARCHAR2(10),
CityCode VARCHAR2(5),
UserGrade NUMBER(4),
UserType NUMBER(4),
OperateTrace VARCHAR2(30),
OperateResult NUMBER(4),
PressDate VARCHAR2(20),
KeyTrace VARCHAR2(10),
ExitDate VARCHAR2(20)
)
ORGANIZATION EXTERNAL(
TYPE ORACLE_LOADER
DEFAULT DIRECTORY testdir
ACCESS PARAMETERS (
RECORDS DELIMITED BY NEWLINE
BADFILE 'bad.txt'
LOGFILE 'log.txt'
READSIZE 10485760
FIELDS TERMINATED BY ','
LDRTRIM
MISSING FIELD VALUES ARE NULL
REJECT ROWS WITH ALL NULL FIELDS
(LogDate,PartID,CalleeNo,CityID,CityCode,UserGrade,UserType,OperateTrace,OperateResult,PressDate,KeyTrace,ExitDate)
)
LOCATION('demo.txt')
)reject limit unlimited
/
3、查看外部表
Txt代码
- SQL> SELECT * FROM demo_ext;
- LOGDATE PARTID CALLEENO CITYID CITYCODE USERGRADE USERTYPE OPERATETRACE OPERATERESULT PRESSDATE KEYTRACE EXITDATE
- -------------------- ------ -------------------- ---------- -------- --------- -------- ------------------------------ ------------- -------------------- ---------- --------------------
- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000005 11
- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000008 11
- 20100830000000 0830 10086 08 0558 32 3 11 100 20100830000009 11
- 20100830000000 0830 10086 17 0567 32 3 11 100 20100830000313 11
- 20100830000001 0830 10086 01 0551 32 3 1911 100 201008300000 11
- 20100830000001 0830 10086 01 0551 32 3 11 100 20100830000011 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000013 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000015 11
- 20100830000001 0830 10086 03 0553 40 2 11 100 20100830000021 11
- 20100830000001 0830 10086 03 0553 40 2 10 80 20100830000145 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000306 11
- 20100830000001 0830 10086 11 0561 32 3 11 100 20100830000311 11
- 20100830000001 0830 10086 07 0557 32 3 11 100 20100830000313 11
- 20100830000001 0830 10086 14 0564 52 1 12 100 20100830000328 12
- 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000006 11
- 20100830000002 0830 10086 14 0564 40 2 11 100 20100830000007 11
- 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000011 11
- 20100830000002 0830 10086 01 0551 40 2 10 80 20100830000017 10
- 18 rows selected
SQL> SELECT * FROM demo_ext; LOGDATE PARTID CALLEENO CITYID CITYCODE USERGRADE USERTYPE OPERATETRACE OPERATERESULT PRESSDATE KEYTRACE EXITDATE -------------------- ------ -------------------- ---------- -------- --------- -------- ------------------------------ ------------- -------------------- ---------- -------------------- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000005 11 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000008 11 20100830000000 0830 10086 08 0558 32 3 11 100 20100830000009 11 20100830000000 0830 10086 17 0567 32 3 11 100 20100830000313 11 20100830000001 0830 10086 01 0551 32 3 1911 100 201008300000 11 20100830000001 0830 10086 01 0551 32 3 11 100 20100830000011 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000013 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000015 11 20100830000001 0830 10086 03 0553 40 2 11 100 20100830000021 11 20100830000001 0830 10086 03 0553 40 2 10 80 20100830000145 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000306 11 20100830000001 0830 10086 11 0561 32 3 11 100 20100830000311 11 20100830000001 0830 10086 07 0557 32 3 11 100 20100830000313 11 20100830000001 0830 10086 14 0564 52 1 12 100 20100830000328 12 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000006 11 20100830000002 0830 10086 14 0564 40 2 11 100 20100830000007 11 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000011 11 20100830000002 0830 10086 01 0551 40 2 10 80 20100830000017 10 18 rows selected
可见外部表已经创建成功！
接着用外部表的数据创建实体表数据：
1、创建实体表
Sql代码
- CREATE TABLE t_demo(
- LogDate VARCHAR2(20),
- PartID CHAR(4),
- CalleeNo VARCHAR2(20),
- CityID VARCHAR2(10),
- CityCode VARCHAR2(5),
- UserGrade NUMBER(4),
- UserType NUMBER(4),
- OperateTrace VARCHAR2(30),
- OperateResult NUMBER(4),
- PressDate VARCHAR2(20),
- KeyTrace VARCHAR2(10),
- ExitDate VARCHAR2(20)
- )
- /
CREATE TABLE t_demo( LogDate VARCHAR2(20), PartID CHAR(4), CalleeNo VARCHAR2(20), CityID VARCHAR2(10), CityCode VARCHAR2(5), UserGrade NUMBER(4), UserType NUMBER(4), OperateTrace VARCHAR2(30), OperateResult NUMBER(4), PressDate VARCHAR2(20), KeyTrace VARCHAR2(10), ExitDate VARCHAR2(20) ) /
2、将外部表数据插入实体表
Sql代码
- SQL> INSERT INTO t_demo SELECT * FROM demo_ext;
- 18 rows inserted
SQL> INSERT INTO t_demo SELECT * FROM demo_ext; 18 rows inserted
3、查看实体表
Sql代码
- SQL> SELECT * FROM t_demo;
- LOGDATE PARTID CALLEENO CITYID CITYCODE USERGRADE USERTYPE OPERATETRACE OPERATERESULT PRESSDATE KEYTRACE EXITDATE
- -------------------- ------ -------------------- ---------- -------- --------- -------- ------------------------------ ------------- -------------------- ---------- --------------------
- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000005 11
- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000008 11
- 20100830000000 0830 10086 08 0558 32 3 11 100 20100830000009 11
- 20100830000000 0830 10086 17 0567 32 3 11 100 20100830000313 11
- 20100830000001 0830 10086 01 0551 32 3 1911 100 201008300000 11
- 20100830000001 0830 10086 01 0551 32 3 11 100 20100830000011 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000013 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000015 11
- 20100830000001 0830 10086 03 0553 40 2 11 100 20100830000021 11
- 20100830000001 0830 10086 03 0553 40 2 10 80 20100830000145 11
- 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000306 11
- 20100830000001 0830 10086 11 0561 32 3 11 100 20100830000311 11
- 20100830000001 0830 10086 07 0557 32 3 11 100 20100830000313 11
- 20100830000001 0830 10086 14 0564 52 1 12 100 20100830000328 12
- 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000006 11
- 20100830000002 0830 10086 14 0564 40 2 11 100 20100830000007 11
- 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000011 11
- 20100830000002 0830 10086 01 0551 40 2 10 80 20100830000017 10
- 18 rows selected
SQL> SELECT * FROM t_demo; LOGDATE PARTID CALLEENO CITYID CITYCODE USERGRADE USERTYPE OPERATETRACE OPERATERESULT PRESSDATE KEYTRACE EXITDATE -------------------- ------ -------------------- ---------- -------- --------- -------- ------------------------------ ------------- -------------------- ---------- -------------------- 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000005 11 20100830000000 0830 10086 01 0551 40 2 11 100 20100830000008 11 20100830000000 0830 10086 08 0558 32 3 11 100 20100830000009 11 20100830000000 0830 10086 17 0567 32 3 11 100 20100830000313 11 20100830000001 0830 10086 01 0551 32 3 1911 100 201008300000 11 20100830000001 0830 10086 01 0551 32 3 11 100 20100830000011 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000013 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000015 11 20100830000001 0830 10086 03 0553 40 2 11 100 20100830000021 11 20100830000001 0830 10086 03 0553 40 2 10 80 20100830000145 11 20100830000001 0830 10086 08 0558 32 3 11 100 20100830000306 11 20100830000001 0830 10086 11 0561 32 3 11 100 20100830000311 11 20100830000001 0830 10086 07 0557 32 3 11 100 20100830000313 11 20100830000001 0830 10086 14 0564 52 1 12 100 20100830000328 12 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000006 11 20100830000002 0830 10086 14 0564 40 2 11 100 20100830000007 11 20100830000002 0830 10086 10 0550 40 2 11 100 20100830000011 11 20100830000002 0830 10086 01 0551 40 2 10 80 20100830000017 10 18 rows selected
*******有关建立外部表的参数说明：
create table extnl_table
(
col01 varchar2(100),
col02 number,
......
)
organization external
( type oracle_loader
default directory "xxx"
access parameters
(
records delimited by 0x'0a'
skip 1 fields
terminated by ','
enclosed by '"'
lrtrim
missing field values are null
reject rows with all null fields
(col01,col02,……)
)
location( 'data.txt'，……)
);
外部表的定义要害是oracle loader参数，records要害字后定义假如识别数据行，fields要害字后定义假如识别字段，常用的如下：
records:
delimited by 'xxx' —— 换行符，常用newline定义换行，假如文件中使用了非凡的字符就要另外定义了；假如是非凡符号，可以使用ox'十六位值'，例如tab(\t)的十六位是9，那么就是delimited by 0x'09'；cr(\r)的十六位是d，那么就是delimited by 0x'0d'。
skip x —— 跳过x行数据，有些文件中第一行是列名，需要跳过第一行，则使用skip 1。
fields：
terminated by 'x' —— 字段分割符。
enclosed by 'x' —— 字段引用符，包含在此符号内的数据都当成一个字段。例如一行数据格式如："abc","a""b,""c,"。使用参数terminated by ',' enclosed by '"'后，系统会读到两个字段，第一个字段的值是abc，第二个字段值是a"b,"c,。
lrtrim —— 删除空白字符。
missing field values are null —— 空缺值都设为null。
假如外部表文件的字段长度和分割符不确定，可以打开文件看看。但是假如文件非常大，比如用十几g，用ultraedit之类的工具打开也许会等十几个小时。那么可以使用分割文件的工具将文件切割成1m左右的小文件，再用记事本打开，复制几行数据出来作测试用。
读取外部表时最常见的问题就是报buffer不足了，假如增大read size还不能解决问题，可能就是断行错误，也许是换行符不对。因为有些换行符在记事本中看不出来，比如说windows的换行符是\n\r，而mac等系统中是line feed(lf, 0x0a)。假如在windows中打开带lf的文件，记事本中显示的是一个黑色的方块，而写字板中是能够显示正确的换行。所以最好使用ultraedit打开，直接看16进制代码，使用delimited by 0x'xx'断行。
还有可能在从外部表读取数据时，读取前面的数据没问题，读到一定的行数就报错。这可能是某行数据出问题导致。只是可以在外部文件目录下发现文件名带有"bad"的日志文件，其中就保存了出错的数据，有记事本打开看看那里出错，是否与外部表定义冲突。
http://lisanlai.iteye.com/blog/780211