在日常工作中；經常會遇到這樣的需求：

• • Oracle 數據表跟文本或者文件格式進行交互；即將指定文件內容導入對應的 Oracle 數據表中；或者從 Oracle 數據表導出。
  • 其他數據庫中的表跟Oracle數據庫進行交互。

　　若是少量數據；可選擇的解決方案有很多。常用的用 Pl/SQL developer工具，或者手動轉換為 INSERT 語句，或者通過API。但數據量大；用上面的方法效率太爛了。本文來說說 Oracle 數據的加載和卸載。

• • Oracle中的DBLINK
  • Oracle加載數據-外部表
  • Oracle加載數據-sqlldr工具
  • Oracle卸載數據-sqludr

一. Oracle 中的 DBLINK

　　在日常工作中；會遇到不同的數據庫進行數據對接；每個數據庫都有著功能；像Oracle有 DBLINK ; PostgreSQL有外部表。

1.1 Oracle DBlink 語法

CREATE [PUBLIC] DATABASE LINK link 
CONNECT TO username 
IDENTIFIED BY password
USING ‘connectstring‘

1.2 Oracle To Mysql

　　在oracle配置mysql數據庫的dblink

二.Oracle加載數據-外部表

　　ORACLE外部表用來存取數據庫以外的文本文件（Text File）或ORACLE專屬格式文件。因此，建立外部表時不會產生段、區、數據塊等存儲結構，只有與表相關的定義放在數據字典中。外部表，顧名思義，存儲在數據庫外面的表。當存取時才能從ORACLE專屬格式文件中取得數據，外部表僅供查詢，不能對外部表的內容進行修改（INSERT、UPDATE、DELETE操作）。不能對外部表建立索引。

2.1 創建外部表需要的目錄

# 創建外部表需要的目錄
SQL> create or replace directory DUMP_DIR as ‘/data/ora_ext_lottu‘; 

Directory created.
# 給用戶授予指定目錄的操作權限
SQL> GRANT READ,WRITE ON DIRECTORY DUMP_DIR TO lottu;

Grant succeeded.

2.2 外部表源文件lottu.txt

10,ACCOUNTING,NEW YORK
20,RESEARCH,DALLAS
30,SALES,CHICAGO
 
40,OPERATIONS,BOSTON

2.3 創建外部表

drop table dept_external purge;

CREATE TABLE dept_external (
   deptno     NUMBER(6),
   dname      VARCHAR2(20),
   loc        VARCHAR2(25) 
)
ORGANIZATION EXTERNAL
(TYPE oracle_loader
 DEFAULT DIRECTORY DUMP_DIR
 ACCESS PARAMETERS
 (
  RECORDS DELIMITED BY newline
  BADFILE ‘lottu.bad‘
  LOGFILE ‘lottu.log‘
  FIELDS TERMINATED BY ","  OPTIONALLY ENCLOSED BY ‘"‘
  (
   deptno     INTEGER EXTERNAL(6),
   dname      CHAR(20),
   loc        CHAR(25)
  )
 )
 LOCATION (‘lottu.txt‘)
)
REJECT LIMIT UNLIMITED;

查看數據

SQL> select * from dept_external;

    DEPTNO DNAME  LOC
---------- -------------------- -------------------------
 10 ACCOUNTING  NEW YORK
 20 RESEARCH  DALLAS
 30 SALES  CHICAGO
 40 OPERATIONS  BOSTON

三. Oracle加載數據-sqlldr工具

3.1 準備實驗對象

　　創建文件lottu.txt；和表tbl_load_01。

[oracle@oracle235 ~]$ seq 1000|awk -vOFS="," ‘{print $1,"lottu",systime()-$1}‘ > lottu.txt
[oracle@oracle235 ~]$ sqlplus lottu/li0924

SQL*Plus: Release 11.2.0.4.0 Production on Mon Aug 13 22:58:34 2018

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> create table tbl_load_01 (id number,name varchar2(10),accountid number);

Table created.

3.2 創建控制文件lottu.ctl

load data
characterset utf8
        infile ‘/home/oracle/lottu.txt‘
        truncate into table tbl_load_01
        fields terminated by ‘,‘
        trailing nullcols
  optionally enclosed by ‘ ‘ TRAILING NULLCOLS
(
 id ,
 name,
 accountid
)

3.3 執行sqlldr

[oracle@oracle235 ~]$ sqlldr ‘lottu/"li0924"‘ control=/home/oracle/lottu.ctl log=/home/oracle/lottu.log bad=/home/oracle/lottu.bad

SQL*Loader: Release 11.2.0.4.0 - Production on Mon Aug 13 23:10:12 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

Commit point reached - logical record count 64
Commit point reached - logical record count 128
Commit point reached - logical record count 192
Commit point reached - logical record count 256
Commit point reached - logical record count 320
Commit point reached - logical record count 384
Commit point reached - logical record count 448
Commit point reached - logical record count 512
Commit point reached - logical record count 576
Commit point reached - logical record count 640
Commit point reached - logical record count 704
Commit point reached - logical record count 768
Commit point reached - logical record count 832
Commit point reached - logical record count 896
Commit point reached - logical record count 960
Commit point reached - logical record count 1000

四.Oracle卸載數據-sqludr

　　sqludr是將Oracle數據表導出到文本中；是牛人樓方鑫開發的。並非Oracle自帶工具；需要下載安裝才能使用。

4.1 sqludr安裝

[oracle@oracle235 ~]$ unzip sqluldr2linux64.zip 
Archive:  sqluldr2linux64.zip
  inflating: sqluldr2linux64.bin     
[oracle@oracle235 ~]$ mv sqluldr2linux64.bin $ORACLE_HOME/bin/sqludr

4.2 查看sqludr幫助

[oracle@oracle235 ~]$ sqludr -?

SQL*UnLoader: Fast Oracle Text Unloader (GZIP, Parallel), Release 4.0.1
(@) Copyright Lou Fangxin (AnySQL.net) 2004 - 2010, all rights reserved.

License: Free for non-commercial useage, else 100 USD per server.

Usage: SQLULDR2 keyword=value [,keyword=value,...]

Valid Keywords:
   user    = username/password@tnsname
   sql     = SQL file name
   query   = select statement
   field   = separator string between fields
   record  = separator string between records
   rows    = print progress for every given rows (default, 1000000) 
   file    = output file name(default: uldrdata.txt)
   log     = log file name, prefix with + to append mode
   fast    = auto tuning the session level parameters(YES)
   text    = output type (MYSQL, CSV, MYSQLINS, ORACLEINS, FORM, SEARCH).
   charset = character set name of the target database.
   ncharset= national character set name of the target database.
   parfile = read command option from parameter file 

  for field and record, you can use ‘0x‘ to specify hex character code,
  \r=0x0d \n=0x0a |=0x7c ,=0x2c, \t=0x09, :=0x3a, #=0x23, "=0x22 ‘=0x27 

4.3 執行sqludr

[oracle@oracle235 ~]$ sqludr lottu/li0924 query="tbl_load_01" file=lottu01.txt field=","
           0 rows exported at 2018-08-13 23:47:55, size 0 MB.
        1000 rows exported at 2018-08-13 23:47:55, size 0 MB.
         output file lottu01.txt closed at 1000 rows, size 0 MB.

7. Oracle數據加載和卸載