The ORACLE Import/Export Utilities

Export, Import are complementary utilities which allow you to write data in an ORACLE-binary format from the database into operating system files and to read data back from those operating system files. EXPORT, IMPORT are used for the following tasks:

backup ORACLE data in operating system files
restore tables that where dropped
save space or reduce fragmentation in the database
move data from one owner to another

Because of the special binary format, files which had been created by the EXPORT utility can only be read by IMPORT. Both tools are only used to maintain ORACLE database objects.
To load data from other systems into the database you have to use SQL*LOADER or other programs. To store data from database into readable operating system files you may use e.g. REPORTS, SQLPLUS.
It is a prerequisite that oraenv or coraenv (if you are working in a c-shell) was executed before you export, import data. Consider, if you stored data in the database by using an national language support (NLS) other than AMERICAN you have to change your environment before import, export.
Example for a german environment:
NLS_LANG=GERMAN_GERMANY.WE8ISO8859P1
export NLS_LANG

EXPORT

Exporting of ORACLE database objects is controlled by parameters. To get familiar with EXPORT parameters type:
exp help=y
You will get a short description and the default settings will be shown.
The EXPORT utility may be used in three ways:

Interactive dialogue
Simply type exp. You will be prompted for your ORACLE userid, password. All other prompts answer by pressing the return key. This is the easiest way to export all data you stored in the ORALE database. You may assign other values than the defaults to the parameters but in most cases it is unnecessary.
Controlled through bypassed parameters
You may bypass parameters when you export data from the database. Type:
exp <userid/password> <parameter>=<value>,<parameter>=<value>,...
Example of exporting scott's tables EMP and DEPT to file empdept.expdat and storing all messages to file empdept.log:
exp scott/tiger file=empdept.expdat tables=(EMP,DEPT) log=empdept.log
Parameterfile controlled
Instead of typing the parameters on the commandline you may use a parameter file where the parameters are stored. The syntax for this method is: exp <userid/password> parfile=<filename>

Do not ignore warnings and messages! Look at your logfile and repeat EXPORT until you get messages like:

About to export specified tables ...
. exporting table                            EMP       14 rows exported
. exporting table                           DEPT        4 rows exported
Export terminated successfully without warnings.

IMPORT

Like EXPORT the IMPORT utility is controlled by parameters. To get familiar with these parameters type: imp help=y
You will get a short description of usage and default settings of parameters.
To start IMPORT simply type imp. You will be prompted for your ORACLE userid, password. The next prompts depend on what you answer. In most cases you may answer the prompts by pressing the return key. But the following prompts you have to answer carefully.

Import file: expdat.dmp >

If your data was exported to file expdat.dmp press return, otherwise enter the filename where the exported data resides.

Ignore create error due to object existence (yes/no): yes >

This is a flag to indicate how object creation errors should be handeld. If you import into an existing table and you set IGNORE=Y, rows could be duplicated if they where already present in the table.

Import entire export file (yes/no): yes > no
Username:

If your exportfile consists of more objects than you want to import, enter no. In this case you will be prompted for the Username (this is normally your ORACLE account).

Enter table names. Null list means all tables for user
Enter table name or . if done:

After entering the username you will be prompted for table names until you press the return key without entering a table name. Than IMPORT will be started.

Instead of the dialogue method you may use parameters. This is analogous to the methods described for EXPORT.
Examples:
imp <userid/password> tables=(table1,table2)
Tables table1, table2 will be imported from the default file export.dmp into the database.
imp <userid/password> parfile=<filename>
Import will be controlled by the named parameterfile.
After importing you should get messages like:

importing SCOTT's objects into SCOTT
. importing table "DEPT"                                     4 rows imported
. importing table "EMP"                                     14 rows imported
Import terminated successfully without warnings.

Imprint

Last update: 17. Jul. 2003

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