How to change the encoding in oracle-Linux Operation and Maintenance-php.cn

In daily operations, databases often require coding changes so that the data in the database can be better managed and processed. Coding changes to Oracle databases are a relatively complex process that require modifications to many elements in the database. This article will introduce the coding modification process of Oracle database and related knowledge, so that you can complete the coding modification work more elegantly.

1. What is encoding?

Coding is the basis for data storage and processing in computers. Each character set and encoding scheme has its own specific characters and how they are parsed. In Oracle database, NLS is the most important parameter related to character set and encoding. NLS parameters are part of the control locale in Oracle database, allowing users to manage different character sets and locales in the same database.

Oracle database uses the Unicode character set. The Unicode character set is a very universal character set that covers almost all letters, numbers, and symbols. It allows users to format and process text in different languages. Therefore, the multi-language support of Oracle database makes it the best choice for processing multi-language text, while also reducing the difficulty of language environment management.

2. Why should we change the encoding?

Once the coding scheme of the Oracle database is established, it may not be changed for many years. But sometimes, enterprises need to achieve more business goals through the database, and these goals need to better support multi-language, non-Latin text, etc., which may require changes in encoding.

Some typical reasons include:

The company expands from domestic to international markets and needs to support multiple languages and character sets;
The company’s character set and encoding There are problems with the solution, such as transmission errors, excessive data capacity, etc.;
The company needs to undergo mergers and acquisitions, and multiple differently encoded data need to be merged into one database;
The company needs to upgrade Oracle database version, you need to change the encoding scheme of the database body when upgrading.

3. Precautions for changing the encoding

Changing the encoding scheme of the Oracle database is a very detailed and complicated task and requires special care. Here are some things to note:

Fully consider the need to change the encoding scheme, and ensure that the new encoding method is chosen correctly. Resolving all relevant issues that may arise in the database should be considered during the planning process and test data should be prepared before testing the new encoding scheme;
Consult with the database administrator to determine the required time frame and Leaders are included in projects. Make sure all associated teams are fully committed to supporting the effort; back up your data and archive it before starting the process. Changing the encoding scheme may result in data loss, so a backup is required to ensure data security;
All related applications should be uninstalled before making encoding changes and reinstalled after the change. This ensures that the program is compatible with the new coding scheme and avoids any potential performance impact; consider changing existing procedures, views, and other database elements in the database. In this way, they can adapt to the new encoding scheme and can be accessed normally;
4. Steps to change the encoding
The following are the main steps to change the encoding scheme of the Oracle database:

Stop the database: The Oracle database needs to be stopped to ensure that there are no corresponding connections and to maintain a consistent state. In some cases, it is necessary to stop the database before backing up the data and starting changes;

Generate and backup DDL statements: Before making changes, DDL statements need to be generated and backed up to the local hard drive. DDL statements contain all the necessary information to apply changes to the Oracle database. Since there may be accidents during the change process, it is recommended to back up safely;

Change the default value of the Oracle database character set: Use the ALTER DATABASE statement to modify the character set of the Oracle database to the new character set scheme;
Change the character set of existing users in the Oracle database: Use the ALTER USER statement to change the character set of all users in the database to the new encoding scheme;
Change the length of the data type: The length of some data types may vary. Changed by the existence of new character sets. For example, the length of a VARCHAR2 field might change from 2000 characters in the old character set scheme to 1000 characters in the new character set scheme. You need to ensure that this result is appropriate in your database and update the length of the corresponding type;
Recompile all stored procedures and functions in the database: After making changes, you need to recompile all stored procedures and functions in the database all procedures and functions. This can be achieved by using the UTLRP.sql script (found in the Oracle installation directory);
Change any application related to the Oracle database: All applications except the database should be considered. The corresponding source code may need to be modified and retested to ensure that the new encoding scheme meets your needs;
Restart the database: After the changes, the Oracle database needs to be restarted to start normal operation.
Summarize
Changing the encoding scheme of an Oracle database is a fairly complex task that requires careful planning, good backups and reliance on responsible DBA and developer support. This article briefly introduces the process of changing the encoding scheme of the Oracle database and provides some considerations to ensure that the project is completed successfully and that both the database and the application can return to good operation.

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