How to set encoding in Oracle

Oracle is a commonly used relational database management system that is used by many businesses and organizations to store and manage data. In actual use, we often need to set the encoding to ensure that the database can correctly handle different character sets and languages. This article explains how to set up encoding in Oracle to better suit the needs of different jobs and applications.

1. Oracle Encoding Overview

Oracle database supports multiple encoding settings, including single-byte encoding and multi-byte encoding. In single-byte encoding, each character occupies one byte; in multi-byte encoding, each character occupies multiple bytes. This encoding method can support more character sets and languages, but it is also more complex. .

In Oracle, commonly used encodings include US7ASCII, WE8ISO8859P1, UTF8 and AL32UTF8, etc. Among them, the US7ASCII encoding is the basic encoding of the English character set. It only supports the ASCII character set and cannot support other languages ​​or non-ASCII characters; the WE8ISO8859P1 encoding is an extended encoding of the ISO-8859-1 traditional European character set and can support major European languages ​​and ASCII characters; UTF8 and AL32UTF8 encodings are both Unicode encodings, which can support all languages ​​and character sets around the world and are more universal encoding methods.

2. Oracle encoding settings

Encoding settings in Oracle need to be set when creating or modifying a database or table. The following describes how to set up the database and tables respectively.

2.1 Database encoding settings

When we create an Oracle database, we need to specify its encoding method. We can set the database encoding in the following two ways:

(1) Use the DBCA tool to set it

When using the Oracle Database Configuration Assistant (DBCA) to create a database, You can set the character set of the database to UTF8 or AL32UTF8 in the "Database Identification" interface. The specific operations are as follows:

• Run the DBCA tool, select the "Create Database" option, and select the type of database to be created;
• In the "Database Identification" interface, set the encoding method It is "Unicode UTF8" or "AL32UTF8";
• Other options can be set according to actual needs to complete the creation of the database.

(2) Manually set the database encoding

We can also manually set the database encoding. The specific operations are as follows:

• Stop the Oracle database service;

• Log in as the SYSDBA user in SQLPLUS Plus and run the following command:

  SQL> startup mount;
  SQL> alter system enable restricted session;
  SQL> alter system set job_queue_processes=0;
  SQL> alter database open;

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• Use the following command to change the default character set of the database:

  SQL> shutdown immediate;
  SQL> startup mount restrict;
  SQL> alter system enable restricted session;
  SQL> alter database character set INTERNAL_USE ZHS16GBK;
  SQL> alter database open;

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The above command sets the database encoding method to GBK. The specific encoding method can be set according to actual needs.

2.2 Table encoding settings

In addition to database encoding, we can also set the encoding method of the table when creating or modifying the table. The specific operations are as follows:

• When creating a table, you can add the CHARACTER SET clause in the table parameters to specify the character set of the table. For example:

  CREATE TABLE mytable (item_id NUMBER, item_name VARCHAR2(30))
    TABLESPACE users
    CHARACTER SET UTF8;

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• When modifying the table, you can use the ALTER TABLE statement to make modifications. For example, change the encoding method of mytable table from WE8ISO8859P1 to UTF8:

  ALTER TABLE mytable MODIFY
    (item_name VARCHAR2(30) CHARACTER SET UTF8);

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One thing to note is that when modifying the table encoding method, you must first save all the data in the original table to avoid data lost.

3. Oracle encoding compatibility

In Oracle, different encoding methods are compatible, which means that we can store data in different encoding methods in the same Store and query in database. When the database requires multiple encoding methods, Oracle will automatically perform character set conversion to ensure that the data can be displayed and processed correctly.

One thing to note is that data loss or damage may occur during character set conversion. Therefore, when performing data storage and query, we should try to use the same encoding method to avoid compatibility issues.

4. Summary

Encoding settings are an important aspect of Oracle database administration. In practical applications, we need to choose the correct encoding method according to actual needs and make corresponding settings. This article introduces the encoding methods commonly used in Oracle and how to set the encoding in databases and tables. By understanding and mastering these contents, we can better utilize Oracle database to meet the needs of different work and applications.

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