Rechercher dans le manuel MySQL

10.9.7 The utf32 Character Set (UTF-32 Unicode Encoding)

Contents

The utf32 character set is fixed length (like ucs2 and unlike utf16). utf32 uses 32 bits for every character, unlike ucs2 (which uses 16 bits for every character), and unlike utf16 (which uses 16 bits for some characters and 32 bits for others).

utf32 takes twice as much space as ucs2 and more space than utf16, but utf32 has the same advantage as ucs2 that it is predictable for storage: The required number of bytes for utf32 equals the number of characters times 4. Also, unlike utf16, there are no tricks for encoding in utf32, so the stored value equals the code value.

To demonstrate how the latter advantage is useful, here is an example that shows how to determine a utf8mb4 value given the utf32 code value:

  1. /* Assume code value = 100cc LINEAR B WHEELED CHARIOT */
  2. CREATE TABLE tmp (utf32_col CHAR(1) CHARACTER SET utf32,
  3.                   utf8mb4_col CHAR(1) CHARACTER SET utf8mb4);
  4. INSERT INTO tmp VALUES (0x000100cc,NULL);
  5. UPDATE tmp SET utf8mb4_col = utf32_col;
  6. SELECT HEX(utf32_col),HEX(utf8mb4_col) FROM tmp;

MySQL is very forgiving about additions of unassigned Unicode characters or private-use-area characters. There is in fact only one validity check for utf32: No code value may be greater than 0x10ffff. For example, this is illegal:

  1. INSERT INTO t (utf32_column) VALUES (0x110000); /* illegal */

Find a PHP function

Document created the 26/06/2006, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/mysql-rf-charset-unicode-utf32.html

The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.

References

  1. View the html document Language of the document:en Manuel MySQL : https://dev.mysql.com/

These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.

Contents Haut