utf8mb4

问题 I'm using docx4j to convert .docx files into html, then saving that data into a MySQL database. Unfortunately, we've hit a snag. When we convert a doc that includes any characters encoded in utf8mb4, and then try and submit that data to our MySQL server, we're hit with a Generic JDBC Exception which states that it doesn't know how to parse the utf8mb4 characters. ERROR pool-3-thread-20 org.hibernate.util.JDBCExceptionReporter - Incorrect string value: '\xEF\xBF\xBD???...' for column 'u

问题 I just setup debian 8.3 on a VM and installed xampp after this Tutorial. Everything is working, until I tried to create a new table: create table testtable ( id int(10) not null auto_increment, firstname varchar(255) collate utf8mb4_german2_ci not null, lastname varchar(255) collate utf8mb4_german2_ci not null, primary key (id), unique key (lastname) )engine = innodb default charset=utf8mb4, collate=utf8mb4_german2_ci I got the error: #1709 - Index column size too large. The maximum column

问题 I discovered (the hard way) that MySQL's UTF8 character set is only 3 bytes. A bit of research shows I can fix this by changing the tables to utilize the utf8mb4 collation and get the full 4 bytes UTF should be. I've done so. My database, tables and columns have all been ALTER ed to utilize this charset. However, I still receive this message if I have data that has unicode code points larger than U+FFFF: Illegal mix of collations (utf8mb4_general_ci,IMPLICIT) and (utf8_general_ci,COERCIBLE)

问题 I have a table like this CREATE TABLE `mb1` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(30) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `u_name` (`name`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; And I insert tow rows insert into mb1(name) values('K'),('Ｋ'); Note, the second K is unicode character +------+-----------+ | name | hex(name) | +------+-----------+ | K | 4B | | Ｋ | EFBCAB | +------+-----------+ Why do they cause unique key

问题 It would seem that using the ASCII charset for most fields and then specify utf8 only for the fields that need it would reduce the amount of I/O the database must perform by 100%. Anyone know if this is true? Update: The above was not really my question. I should have said: use Latin for the default character set and then only specify utf8mb4 only for the fields that need it. The thinking being that: using 1 byte vs 2 bytes should improve I/O by 100%. Sorry for the confusion. 回答1: @RickJames

问题 In order to use 4-byte utf8mb4 in MySQL (5.6.11), I have set the following variables in the my.ini file ( my.cnf is not found). This file is located in a hidden folder named Application Data ( C:\Documents and Settings\All Users\Application Data\MySQL\MySQL Server 5.6 ) on Windows XP. It is not available under the installation directory. [client] port=3306 default-character-set=utf8mb4 [mysql] default-character-set=utf8mb4 [mysqld] init-connect='SET NAMES utf8mb4' collation_server=utf8mb4

问题 I have a website that connects with iPhone and Android users. They sometimes use UTF8MB4 characters (Emoji). When inserting those characters in strings in my MySQL database (formatted UTF8) the data was cropped at the first emoji. Unfortunately, my hoster is running MySQL 5.1.66 and is not planning to update to a newer version yet. So what is the best solution for temporary use without switching the encoding? 回答1: I have searched the web for many hours and I came to this solution which I want

问题 I know there have been plenty of questions about this, but I think my math is right. MySQL reserves 3 bytes per UTF8 character. MyISAM allows keys of length 1000 bytes. My UTF8 VARCHAR(255) should be 255 * 3 = 765 bytes Unless UNQUE requires an extra 200+ bytes per entry, why doesn't this work? mysql> ALTER TABLE entry ADD UNIQUE INDEX (name(255)); ERROR 1071 (42000): Specified key was too long; max key length is 1000 bytes Is there anything I can do about this? EDIT: It turns out the limit

问题 I am using a utf8 charset mysql tables in a mysql 5.1 server, which does not support utf8mb4 encoding in tables. When inserting 4-byte encoded utf8 characters like "𡃁","𨋢","𠵱","𥄫","𠽌","唧","𠱁" . The table will popup error or skip the following texts. How can I programmatically detect 4-byte encoded utf8 characters in PHP and replace them? 回答1: The following regular expression will replace 4-byte UTF-8 characters: function replace4byte($string, $replacement = '') { return preg_replace('%(?:

问题 This is my environment: Client -> iOS App, Server ->PHP and MySQL. The data from client to server is done via HTTP POST. The data from server to client is done with json. I would like to add support for emojis or any utf8mb4 character in general. I'm looking for the right way for dealing with this under my scenario. My questions are the following: Does POST allow utf8mb4, or should I convert the data in the client to plain utf8? If my DB has collation and character set utf8mb4, does it mean I