Oracle教程之管理表（六）--Oracle外部表的管理

外部表是表结构被存放在数据字典，而表数据被存放在OS文件的表。通过使用外部表，不仅可以在数据库中查询OS文件的数据，还可以使用INSERT方式将OS文件数据装载到数据库中，从而实现SQL*Loader所提供的功能。建立外部表后，可以查询外部表的数据，在外部表上执行连接查询，或对外部表的数据进行排序。需要注意，外部表上不能执行DML修改，也不能在外部表上建立索引。1、建立外部表——准备工作：[oracle@solaris10 ~]$mkdir /export/home/oracle/dat[oracle@solaris10 ~]$cd /export/home/oracle/dat[oracle@solaris10 dat]$vi empxt1.dat360,Jane,Janus,ST_CLERK,121,17-MAY-2001,3000,0,50,jjanus361,Mark,Jasper,SA_REP,145,17-MAY-2001,8000,.1,80,mjasper362,Brenda,Starr,AD_ASST,200,17-MAY-2001,5500,0,10,bstarr363,Alex,Alda,AC_MGR,145,17-MAY-2001,9000,.15,80,aalda[oracle@solaris10 dat]$vi empxt2.dat401,Jesse,Cromwell,HR_REP,203,17-MAY-2001,7000,0,40,jcromwel402,Abby,Applegate,IT_PROG,103,17-MAY-2001,9000,.2,60,aapplega403,Carol,Cousins,AD_VP,100,17-MAY-2001,27000,.3,90,ccousins404,John,Richardson,AC_ACCOUNT,205,17-MAY-2001,5000,0,110,jrichard——建立对应的目录：SQL> conn /as sysdbaConnected.SQL> create or replace directory admin_dat_dir2 as '/export/home/oracle/dat';Directory created.SQL> create or replace directory admin_log_dir2 as '/export/home/oracle/log';Directory created.SQL> create or replace directory admin_bad_dir2 as '/export/home/oracle/bad';Directory created.SQL> ![oracle@solaris10 ~]$mkdir /export/home/oracle/{log,bad}[oracle@solaris10 ~]$ls1 Documents core dat local.login shell1.sql afiedt.buf cr_anny_db.sql hell.txt local.profile x86Desktop bad cr_dict.sql local.cshrc log——授权scott 可以访问所建立的目录SQL> grant read on directory admin_dat_dir to scott;Grant succeeded.SQL> grant write on directory admin_log_dir to scott;Grant succeeded.SQL> grant write on directory admin_bad_dir to scott;Grant succeeded.——建立外部表SQL> conn scott/tigerConnected.SQL>CREATE TABLE admin_ext_employees(employee_id NUMBER(4),first_name VARCHAR2(20),last_name VARCHAR2(25),job_id VARCHAR2(10),manager_id NUMBER(4),hire_date DATE,salary NUMBER(8,2),commission_pct NUMBER(2,2),department_id NUMBER(4),email VARCHAR2(25))ORGANIZATION EXTERNAL(TYPE ORACLE_LOADERDEFAULT DIRECTORY admin_dat_dirACCESS PARAMETERS(records delimited by newlinebadfile admin_bad_dir:'empxt%a_%p.bad'logfile admin_log_dir:'empxt%a_%p.log'fields terminated by ','missing field values are null( employee_id, first_name, last_name, job_id, manager_id,hire_date char date_format date mask "dd-mon-yyyy",salary, commission_pct, department_id, email))LOCATION ('empxt1.dat', 'empxt2.dat'))PARALLELREJECT LIMIT UNLIMITED;Table created.SQL> select * from tab;TNAME TABTYPE CLUSTERID------------------------------ ------- ----------DEPT TABLEEMP TABLEBONUS TABLESALGRADE TABLETEST TABLEADMIN_EXT_EMPLOYEES TABLE6 rows selected.——查询外部表记录SQL> select * from ADMIN_EXT_EMPLOYEES;EMPLOYEE_ID FIRST_NAME LAST_NAME JOB_ID MANAGER_ID HIRE_DATE SALARY COMMISSION_PCT DEPARTMENT_ID EMAIL----------- ---------- ---------- ---------- ---------- ------------------- ---------- -------------- ------------- ----------360 Jane Janus ST_CLERK 121 2001-05-17 00:00:00 3000 0 50 jjanus361 Mark Jasper SA_REP 145 2001-05-17 00:00:00 8000 .1 80 mjasper362 Brenda Starr AD_ASST 200 2001-05-17 00:00:00 5500 0 10 bstarr363 Alex Alda AC_MGR 145 2001-05-17 00:00:00 9000 .15 80 aalda401 Jesse Cromwell HR_REP 203 2001-05-17 00:00:00 7000 0 40 jcromwel402 Abby Applegate IT_PROG 103 2001-05-17 00:00:00 9000 .2 60 aapplega403 Carol Cousins AD_VP 100 2001-05-17 00:00:00 27000 .3 90 ccousins404 John Richardson AC_ACCOUNT 205 2001-05-17 00:00:00 5000 0 110 jrichard10 rows selected.只能读，不能做dmlSQL> delete from ADMIN_EXT_EMPLOYEES;delete from ADMIN_EXT_EMPLOYEES*ERROR at line 1:ORA-30657: operation not supported on external organized table——把外部表数据插入到oracle 表里SQL> create table employees as select * from admin_ext_employees where 1=2;Table created.SQL> insert into employees select * from admin_ext_employees;10 rows created.SQL> select * from employees;EMPLOYEE_ID FIRST_NAME LAST_NAME JOB_ID MANAGER_ID HIRE_DATE SALARY COMMISSION_PCT DEPARTMENT_ID EMAIL----------- ---------- ---------- ---------- ---------- ------------------- ---------- -------------- ------------- ----------401 Jesse Cromwell HR_REP 203 2001-05-17 00:00:00 7000 0 40 jcromwel402 Abby Applegate IT_PROG 103 2001-05-17 00:00:00 9000 .2 60 aapplega403 Carol Cousins AD_VP 100 2001-05-17 00:00:00 27000 .3 90 ccousins404 John Richardson AC_ACCOUNT 205 2001-05-17 00:00:00 5000 0 110 jrichard360 Jane Janus ST_CLERK 121 2001-05-17 00:00:00 3000 0 50 jjanus361 Mark Jasper SA_REP 145 2001-05-17 00:00:00 8000 .1 80 mjasper362 Brenda Starr AD_ASST 200 2001-05-17 00:00:00 5500 0 10 bstarr363 Alex Alda AC_MGR 145 2001-05-17 00:00:00 9000 .15 80 aalda10 rows selected.
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