mysqld 升級到8以上遇到的問題

coav4u

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- b5 l3 V  T7 a" D2 `5 |* X$ Hphp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)

5 j) g9 z! e- |mysqli_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:
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:
vi /etc/my.cnf  加入下列:
" P# u# [% I& i! x. u+ ^" C" V[mysqld]

$ o8 K+ P8 K+ g" A" k' _, M+ Echaracter-set-server=utf8
default_authentication_plugin=mysql_native_password
validate_password.policy=LOW
) |; z% E8 Y! X- z; C8 U1 j[mysql]
  A9 V6 I) V( G* fdefault-character-set=utf8

[client]
default-character-set=utf8

然後重啟mysqld
+ P& A2 H4 Z  j2 y, l2 qservice mysqld restart

2 l8 |! A4 c3 _9 a9 c+ X重啟後可能須做下列動作:
- N8 D! k% s8 {3 k' \# ^# R, ymysql -u roor -p  
# P5 C; |7 f! w1 E0 y" e% eSHOW VARIABLES LIKE 'validate_password%';
1 L" Z( M8 R! z" XSET GLOBAL validate_password_policy=LOW;ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '你的密碼';搞定!!
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8 `9 [" Z0 i6 Y- e! ~- S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 ~~~
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1. <?
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2. $hostname = "x.x.x.x";
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3. $database = "db_name";
   
4. $username = "user_name";
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5. $password = "pwd";
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6. 
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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));
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12. echo $rec['total'];
    
13. mysqli_close($conn);
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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
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2. Stack trace:
   
3. #0 {main}
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4.   thrown in /test/connectmysql8.php on line 9
   
5. 
   
6. Fatal error: Uncaught Error: Call to undefined function mysqli_connect() in /test/connectmysql8.php:9
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7. Stack trace:
   
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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, O) g1 R8 a/ X[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.
6 U3 m% D6 m, N7 W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)
(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
, i# p8 A$ j; @+ MSELECT COUNT(*) FROM common_usergroup WHERE type='special' and system>0
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$ h3 f& q& o; o1 a; J(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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# ?: f* z1 C/ P$ _  m4 l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`。

第一個錯誤需要找到Discuz!目錄中的source\class\table\table_common_usergroup.php，
+ F* ~# N# `; }1 B7 o9 O" A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。

* h' O' Z5 n. x. x, X第二個錯誤需要找到Discuz!目錄下中的source\class\table\table_forum_announcement.php，
9 `) o! M& j& G7 L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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1 a1 m6 d* o  H; V( F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。
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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。
$ g' {: n5 N  E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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