Oracle 11g数据库之数据导入导出与事物

Oracle 11g数据库之数据导入导出与事物

在使用Oracle数据库中对备份恢复是最关键的，当数据库出现故障时可以及时恢复减少不必要的损失。下面我将简单介绍一下导入导出数据库,方案,表,和在使用的过程当中事物的作用。
1.导出数据表
[oracle@CentOS ~]$ exp scott/system tables=t file='/home/oracle/t.dump' log='/home/oracle/t.log';    --导出scott用户中的t表数据(tables=可以写多个表,full=y  全部导出,ignore=y  表示忽略重复的数据)
Export: Release 11.2.0.1.0 - Production on Mon Feb 17 16:28:04 2014
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses WE8MSWIN1252 character set (possible charset conversion)
About to export specified tables via Conventional Path ...
. . exporting table                              T          1 rows exported
Export terminated successfully without warnings.
[oracle@centos ~]$

2.导入数据表
[oracle@centos ~]$ sqlplus
SQL*Plus: Release 11.2.0.1.0 Production on Mon Feb 17 16:29:13 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
Enter user-name: scott
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> drop table t;    --删除我刚才导出的表
Table dropped.
SQL> commit;
Commit complete.
SQL> quit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@centos ~]$ imp scott/system tables=t file='/home/oracle/t.dump';  --导入数据表
Import: Release 11.2.0.1.0 - Production on Mon Feb 17 16:29:58 2014
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export file created by EXPORT:V11.02.00 via conventional path
import done in US7ASCII character set and AL16UTF16 NCHAR character set
import server uses WE8MSWIN1252 character set (possible charset conversion)
. importing SCOTT's objects into SCOTT
. importing SCOTT's objects into SCOTT
. . importing table                            "T"          1 rows imported
Import terminated successfully without warnings.
[oracle@centos ~]$ sqlplus
SQL*Plus: Release 11.2.0.1.0 Production on Mon Feb 17 16:30:03 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
Enter user-name: scott
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select * from t;    --成功导入
A
----------
1
SQL>

3.导出用户下的所有表(scott)
[oracle@centos ~]$ exp scott/system  file='/home/oracle/scott.dump';  --导入scott自己的所有表(exp scott/system owner=用户名 file='路径'  --导出其它用户下的表)
Export: Release 11.2.0.1.0 - Production on Mon Feb 17 16:34:07 2014
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses WE8MSWIN1252 character set (possible charset conversion)
. exporting pre-schema procedural objects and actions
. exporting foreign function library names for user SCOTT
. exporting PUBLIC type synonyms
. exporting private type synonyms
. exporting object type definitions for user SCOTT
About to export SCOTT's objects ...
. exporting database links
. exporting sequence numbers
. exporting cluster definitions
. about to export SCOTT's tables via Conventional Path ...
. . exporting table                          DEPT          4 rows exported
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
. . exporting table                            EMP        12 rows exported
EXP-00091: Exporting questionable statistics.
EXP-00091: Exporting questionable statistics.
. . exporting table                      SALGRADE          5 rows exported
EXP-00091: Exporting questionable statistics.
. . exporting table                  SYS_TEMP_FBT
. . exporting table                              T          1 rows exported
. . exporting table                          TONG1        14 rows exported
EXP-00091: Exporting questionable statistics.
. exporting synonyms
. exporting views
. exporting stored procedures
. exporting operators
. exporting referential integrity constraints
. exporting triggers
. exporting indextypes
. exporting bitmap, functional and extensible indexes
. exporting posttables actions
. exporting materialized views
. exporting snapshot logs
. exporting job queues
. exporting refresh groups and children
. exporting dimensions
. exporting post-schema procedural objects and actions
. exporting statistics
Export terminated successfully with warnings.
[oracle@centos ~]$

4.导入用户下的所有表(scott)
[oracle@centos ~]$ sqlplus
SQL*Plus: Release 11.2.0.1.0 Production on Mon Feb 17 16:39:53 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
Enter user-name: scott
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> drop table t;    --删除表
Table dropped.
SQL> drop table tong1;
Table dropped.
SQL> commit;
Commit complete.
SQL> quit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@centos ~]$ imp scott/system file='/home/oracle/scott.dump';  --导入scott用户下的表
Import: Release 11.2.0.1.0 - Production on Mon Feb 17 16:40:39 2014
Copyright (c) 1982, 2009, Oracle and/or its affiliates.  All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export file created by EXPORT:V11.02.00 via conventional path
import done in US7ASCII character set and AL16UTF16 NCHAR character set
import server uses WE8MSWIN1252 character set (possible charset conversion)
. importing SCOTT's objects into SCOTT
IMP-00015: following statement failed because the object already exists:
"CREATE TABLE "DEPT" ("DEPTNO" NUMBER(2, 0), "DNAME" VARCHAR2(14), "LOC" VAR"
"CHAR2(13))  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 STORAGE(INITIAL 6"
"5536 NEXT 1048576 MINEXTENTS 1 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DE"
"FAULT)                    LOGGING NOCOMPRESS"
IMP-00015: following statement failed because the object already exists:
"CREATE TABLE "EMP" ("EMPNO" NUMBER(4, 0), "ENAME" VARCHAR2(10), "JOB" VARCH"
"AR2(9), "MGR" NUMBER(4, 0), "HIREDATE" DATE, "SAL" NUMBER(7, 2), "COMM" NUM"
"BER(7, 2), "DEPTNO" NUMBER(2, 0))  PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRAN"
"S 255 STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 FREELISTS 1 FREELIST "
"GROUPS 1 BUFFER_POOL DEFAULT)                    LOGGING NOCOMPRESS"
IMP-00015: following statement failed because the object already exists:
"CREATE TABLE "SALGRADE" ("GRADE" NUMBER, "LOSAL" NUMBER, "HISAL" NUMBER)  P"
"CTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 STORAGE(INITIAL 65536 NEXT 104"
"8576 MINEXTENTS 1 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)      "
"            LOGGING NOCOMPRESS"
IMP-00015: following statement failed because the object already exists:
"CREATE GLOBAL TEMPORARY TABLE "SYS_TEMP_FBT" ("SCHEMA" VARCHAR2(32), "OBJEC"
"T_NAME" VARCHAR2(32), "OBJECT#" NUMBER, "RID" UROWID(4000), "ACTION" CHAR(1"
")) ON COMMIT PRESERVE ROWS "
. . importing table                            "T"          1 rows imported
. . importing table                        "TONG1"        14 rows imported
Import terminated successfully with warnings.
[oracle@centos ~]$ sqlplus
SQL*Plus: Release 11.2.0.1.0 Production on Mon Feb 17 16:40:47 2014
Copyright (c) 1982, 2009, Oracle.  All rights reserved.
Enter user-name: scott
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select * from tab;    --查看表被导入成功
TNAME                  TABTYPE  CLUSTERID
------------------------------ ------- ----------
BONUS                  TABLE
DEPT                  TABLE
TNAME                  TABTYPE  CLUSTERID
------------------------------ ------- ----------
EMP                TABLE
SALGRADE              TABLE
SYS_TEMP_FBT              TABLE
T                  TABLE
TONG1                  TABLE
16 rows selected.
SQL>

5.导出整个数据库
[oracle@centos ~]$ exp system/system file='/home/oracle/database.dump' log='/home/oracle/database.log';    --导出整个数据库

6.事物
一、什么是事务
      事务用于保证数据的一致性，它由一组相关的dml语句组成，该组的dml语句要么全部成功，要们全部失败。如：网上转帐就是典型的要用事务来处理，用以保证数据的一致性。
二、事务和锁
      当执行事务操作时，Oracle会在被作用的表上加锁，防止其他用户改表。
三、提交事务
      在执行使用commit语句可以提交事务，当执行了commit语句后，会确认事务的变化，结束事务，删除保存点，释放锁。当使用commit语句结束事务之后，其他会话将可以查看到事务变化后的新数据。
四、回退事务
    在介绍回退事务前，我们先介绍一下保存点（savepoint）的概念和作用，保存点是事务中的一点，用于取消部分事务，当结束事务时，会自动的删除该事务所定义的所有保存点。当执行rollback时，通过制定保存点可以回退到指定的点。
五、只读事务
    只读事务是指只允许执行查询的操作，而不允许执行任何其他dml操作的事务，使用只读事务可以确保用户只能取得某时间点的数据。
设置只读事务：
SQL> savepoint qw;    --创建保存点
Savepoint created.
SQL> delete from t;    --删除表中的数据，不能commit提交
2 rows deleted.
SQL> select * from t;
no rows selected
SQL> rollback to qw;    --回退到保存点
Rollback complete.
SQL> select * from t;    --数据回来了
A
----------
1
2
sql>set transaction read only;    --数据库的表只能查询不能修改和删除