Using Import Utility

Objects exported by export utility can only be imported by Import utility. Import utility can  run in Interactive mode or command line mode.

You can let Import prompt you for parameters by entering the IMP command followed by your username/password:

     Example: IMP SCOTT/TIGER

Or, you can control how Import runs by entering the IMP command followed

by various arguments. To specify parameters, you use keywords:

     Format:  IMP KEYWORD=value or KEYWORD=(value1,value2,...,valueN)

     Example: IMP SCOTT/TIGER IGNORE=Y TABLES=(EMP,DEPT) FULL=N

               or TABLES=(T1:P1,T1:P2), if T1 is partitioned table

USERID must be the first parameter on the command line.

Example Importing Individual Tables

To import individual tables from a full database export dump file give the following command

$imp scott/tiger FILE=myfullexp.dmp FROMUSER=scott TABLES=(emp,dept)

This command will import only emp, dept tables into Scott user and you will get a output similar  to as shown below

Export file created by EXPORT:V10.00.00 via conventional path
import done in WE8DEC character set and AL16UTF16 NCHAR character set
. importing SCOTT's objects into SCOTT
. . importing table                         "DEPT"          4 rows imported
. . importing table                          "EMP"         14 rows imported

Import terminated successfully without warnings.

Example, Importing Tables of One User account into another User account

For example, suppose Ali has exported tables into a dump file mytables.dmp. Now Scott wants to import these tables. To achieve this Scott will give the following import command

$imp scott/tiger  FILE=mytables.dmp FROMUSER=ali TOUSER=scott

Then import utility will give a warning that tables in the dump file was exported by user Ali and not you and then proceed.

Example Importing Tables Using Pattern Matching

Suppose you want to import all tables from a dump file whose name matches a particular pattern. To do so, use “%” wild character in TABLES option. For example, the following command will import all tables whose names starts with alphabet “a” and those tables whose name contains alphabet “d”

$imp scott/tiger FILE=myfullexp.dmp FROMUSER=scott TABLES=(a%,%d%)

Migrating a Database across platforms.

The Export and Import utilities are the only method that Oracle supports for moving an existing Oracle database from one hardware platform to another. This includes moving between UNIX and NT systems and also moving between two NT systems running on different platforms.

The following steps present a general overview of how to move a database between platforms.

1. As a DBA user, issue the following SQL query to get the exact name of all tablespaces. You will need this information later in the process.

SQL> SELECT tablespace_name FROM dba_tablespaces;

2. As a DBA user, perform a full export from the source database, for example:

$ exp system/manager FULL=y FILE=myfullexp.dmp

3. Move the dump file to the target database server. If you use FTP, be sure to copy it in binary format (by entering binary at the FTP prompt) to avoid file corruption.
4. Create a database on the target server.
5. Before importing the dump file, you must first create your tablespaces, using the information obtained in Step 1. Otherwise, the import will create the corresponding datafiles in the same file structure as at the source database, which may not be compatible with the file structure on the target system.
6. As a DBA user, perform a full import with the IGNORE parameter enabled:

$ imp system/manager FULL=y IGNORE=y FILE=myfullexp.dmp

Using IGNORE=y instructs Oracle to ignore any creation errors during the import and permit the import to complete.

7. Perform a full backup of your new database.