A preliminary discussion on the character set problem (I.)

Problem

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Oracle Global Support (that is, globalization Support) allows us to store and retrieve data using local languages and formats. With global support, Oracle can support multiple languages and character sets to showcase the power of the database.
Because of the complexity of the common storage of different languages and character sets, the character set has become a common problem.
This article attempts to discuss some common problems, hoping to share some practical experience to everyone!

1. Basic knowledge of character sets
If you start from scratch, the character set's earliest encoding scheme comes from the ASCII.
This is also our most common way of coding. The program originated in the early 1960, initially the United States Library of Congress to develop the United States library industry as a common standard for bibliographic exchange, and finally perfect to become the United States National standard ASCII (American Standard codefor Information Interchange), then further evolved into a worldwide computer character encoding standard ISO646 (its full name is 7-bit coded character set for information). Become the basis of the computer coding scheme.
The earliest supported encoding scheme for Oracle databases is US7ASCII.
But we know that English characters are usually stored in one byte, a 7-bit encoding scheme can represent a maximum of 128 characters, and an extended 8-bit encoding scheme can only represent 256 characters, which is far from meeting the needs of computer development, and requires more yards for complex character storage in Asian countries. So the various coding schemes are born.

In order to accommodate all the characters and symbols of all languages in the world, to solve the compatibility and conversion between different codes, 1991 years, more than 10 companies jointly funded the formation of the Unicode Association, followed by the Unicode code generation.
The Unicode Association's slogan is: Give each character a unique number, no matter what platform, no matter what the program, no matter what language.
Initially Unicode encoding is encoded using 2-byte (16bit), but can only hold 65,536 characters, is still not enough to use, and later expanded, That is, the Unicode3.1 standard, added additional character definition, now Unicode4.0 standard has been released, specific reference to the official Unicode site:

www.unicode.org


The Unicode encoding scheme has three implementation criteria:
UTF-8
USC-2
UTF-16
Oracle supports UTF-8 encoding starting from 7.2, providing Unicode encoding support.

According to various standards, Oracle recommends that you use a Unicode encoding scheme if your database requires different symbols and characters in different languages. It is true that Unicode schemes can represent more characters, but because of the need for additional storage space and network transport due to multiple bits of storage, it is still prudent to choose the most appropriate database character set.