How to modify the character set of Oracle database

In Oracle database, character set is very important. Character sets are used to define how data in a database is encoded. In some cases, you may need to modify the character set in the database, for example if you want to change from a Western language to Chinese or from an old character set to a new character set. So how to modify the character set in Oracle database? This article will introduce it to you in detail.

What is a character set?

Character set is a set that contains a set of characters and their corresponding binary encodings. In the Oracle database, data is stored on disk in binary form, and the character set is used to map characters into binary encoding. Oracle database supports multiple character sets, each character set corresponds to a unique binary encoding.

How to check the current character set?

In Oracle database, you can use the following command to view the current character set:

SELECT parameter, value 
  FROM nls_database_parameters 
 WHERE parameter LIKE '%CHARACTERSET';

The output result will display the character set of the database.

How to modify the character set of the database?

If you want to modify the character set of the Oracle database, there are two methods:

1. Use Database Configuration Assistant (DBCA)

In the Oracle database, DBCA is a visual tool that helps you configure and manage your database. You can use DBCA to modify the character set of the database.

The following are the steps to modify the character set:

1. Run DBCA on the server.
2. Select "Modify Database".
3. Select to modify the character set of the database and click "Next".
4. Select the desired character set and click "Next".
5. Enter the password of the SYS user.
6. Click "Finish" and wait for the process to complete.
7. Restart the database for changes to take effect.

2. Use the SQL command line

You can also use the SQL command line to modify the character set of the database. Here are the steps to modify the character set:

1. Log in to SQL Plus using the SYS user.
2. Enter database upgrade mode:

SQL> STARTUP UPGRADE

3. Modify the database character set to the required character set:

SQL> ALTER SYSTEM SET NLS_CHARACTERSET = 'AL32UTF8' SCOPE=SPFILE;

Note: In the above In the command, we change the character set to AL32UTF8.

4. Start the database:

SQL> SHUTDOWN IMMEDIATE;
SQL> STARTUP;

Summary

Character set is a very important part of the Oracle database. In some cases, you may need to modify the database character set. At this point you can use DBCA or the SQL command line to complete this operation. We hope this article can help you successfully modify the character set of your Oracle database.

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