mysqld 升級到8以上遇到的問題

coav4u

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php連到mysql出現2行errors : (discuz網頁出現的是連接到mysql錯誤表格,需自行寫一隻連接mysql的php程式來測試)
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* a3 ~8 P; e6 N5 E. Amysqli_real_connect(): Server sent charset (255) unknown to the client. Please, report to the developers
mysqli_real_connect(): (HY000/2054): Server sent charset unknown to the client. Please, report to the developers
原因:
8 Y6 O  V0 Z. b. \' s: A4 b在MySQL 8.0.21中，caching_sha2_password是默認的身份驗證插件，而不是以往的mysql_native_password。所以和php不相容。可以降級php，也可以修改MySQL的配置。 吾人決定修改MySQL的配置:
* ^" u; K" g+ x, |  Ivi /etc/my.cnf  加入下列:
[mysqld]
% d! e4 F3 J0 d2 b% u" \
" |  w1 s- [! W- Scharacter-set-server=utf8
2 w9 C7 Y3 b. K% s9 y% W# Ldefault_authentication_plugin=mysql_native_password
validate_password.policy=LOW
( G  E0 A* d7 w) ?% G! J[mysql]
default-character-set=utf8
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6 S# h# W+ W0 p0 x  V2 R6 M9 x6 L7 b8 v[client]
default-character-set=utf8
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然後重啟mysqld
service mysqld restart

# M) s6 S9 a9 I9 }重啟後可能須做下列動作:
mysql -u roor -p  
) E  h2 C6 _8 n' X0 aSHOW VARIABLES LIKE 'validate_password%';
% L" q& J  t3 q0 ySET GLOBAL validate_password_policy=LOW;ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '你的密碼';搞定!!

2 Y0 d& r. c! _" U0 a註: mysqld啟動時,在/var/log/mysql/mysqld.log紀錄著:註: 可以先寫支php程式以測試 ~~~

1. <?
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2. $hostname = "x.x.x.x";
   
3. $database = "db_name";
   
4. $username = "user_name";
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5. $password = "pwd";
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6. 
   
7. $conn = mysqli_connect($hostname, $username, $password,$database) or trigger_error(mysql_error(),E_USER_ERROR);
   
8. mysqli_query($conn ,"SET NAMES utf8");
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9. 
   
10. $sql = "select count(*) as total from " .  "table_name";
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11. $rec = mysqli_fetch_assoc(mysqli_query( $conn,$sql));
    
12. echo $rec['total'];
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13. mysqli_close($conn);
    
14. ?>

複製代碼

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當php 7.2.24  connect to mysql server,出現 :

1. PHP Fatal error:  Uncaught Error: Call to undefined function mysqli_connect() in /test/connectmysql8.php:9
   
2. Stack trace:
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3. #0 {main}
   
4.   thrown in /test/connectmysql8.php on line 9
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5. 
   
6. Fatal error: Uncaught Error: Call to undefined function mysqli_connect() in /test/connectmysql8.php:9
   
7. Stack trace:
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8. #0 {main}
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9.   thrown in /test/connectmysql8.php on line 9

複製代碼

這是版本相依的問題,只要 yum install php-mysqlnd  或 yum install php-mysqli 即可
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, w* y+ l3 ~2 ][Warning] [MY-013242] [Server] --character-set-server: 'utf8' is currently an alias for the character set UTF8MB3, but will be an alias for UTF8MB4 in a future release. Please consider using UTF8MB4 in order to be unambiguous.
: g$ s# F' z& U7 c* o8 M8 F2 F" [說明: 千萬不能照它建議用"UTF8MB4",否則無法成功啟動
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(2)
! W0 p; @$ m* H. ?) y& r. L3 k  [8 Q(1064) You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'system>0' at line 1
SELECT COUNT(*) FROM common_usergroup WHERE type='special' and system>0
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(1064) You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'groups = '' AND starttime<=1532077291 AND (endtime>=1532077291 OR endtime=0) ORD' at line 1
SELECT * FROM forum_announcement WHERE type!=2 AND groups = '' AND starttime<=1532077291 AND (endtime>=1532077291 OR endtime=0) ORDER BY displayorder, starttime DESC, id DESC LIMIT 1
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因為MySQL 8.0+將system和groups作為了關鍵字，所以不能直接在SQL中將system和groups這兩個詞作為數據庫、數據表、數據表字段中的任意一種使用，如果數據庫名或數據表名或數據表字段名使用了system或groups作為名字，必須使用一對反引號引用起來。寫作`system`或`groups`。
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% G( x: _! M* |# Z( y第一個錯誤需要找到Discuz!目錄中的source\class\table\table_common_usergroup.php，
將文件中所有的system全部改成`system`，保存後重新上傳到服務器的相同目錄即可。
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& X8 Y0 W9 N4 X7 ]% [: F第二個錯誤需要找到Discuz!目錄下中的source\class\table\table_forum_announcement.php，
將文件中所有的groups全部改為`groups`，保存後重新上傳到服務器的相同目錄即可。
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如果在MySQL 8+環境下安裝Discuz!，在安裝前需要給install\data\install.sql文件中沒有加引號的所有system逐一添加一對反引號保存重新上傳到服務器的相同目錄，否則也會出現SQL語法錯誤。

% ]$ Y6 q' B& Q為了避免語法錯誤，在寫SQL語句時，一定要為所有的數據庫名、數據表名、數據表字段名全部添加一對反引號，像Discuz!這樣的寫法是很不妥的。
& [" l' F  l% v7 v, F# Y$ y" W$ u" A以上參考:   升級到 MySQL 8.0+ 後Discuz! 更新緩存時出現SQL語法錯誤
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