mysqld 升級到8以上遇到的問題

coav4u

(1)
1 p5 f. |% C- c  sphp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)

mysqli_real_connect(): Server sent charset (255) unknown to the client. Please, report to the developers
7 L- x. v& @2 P; Q8 p* w7 \. |2 S8 e- mmysqli_real_connect(): (HY000/2054): Server sent charset unknown to the client. Please, report to the developers
原因:
5 L0 T% Q8 v) m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:
# _6 i- }. d% wvi /etc/my.cnf  加入下列:
[mysqld]

6 T0 X6 G$ [& z0 bcharacter-set-server=utf8
default_authentication_plugin=mysql_native_password
* i( u: V! e7 {3 U; q7 Ovalidate_password.policy=LOW
5 B6 N! U( _8 O[mysql]
# b/ n' ^4 t3 `7 gdefault-character-set=utf8
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7 n0 N8 L5 X9 k[client]
& t7 V7 O6 `, ~1 Q& Gdefault-character-set=utf8
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然後重啟mysqld
service mysqld restart
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  [) m& v; `6 l7 h重啟後可能須做下列動作:
mysql -u roor -p  
SHOW VARIABLES LIKE 'validate_password%';
SET 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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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. <?
   
2. $hostname = "x.x.x.x";
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3. $database = "db_name";
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4. $username = "user_name";
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5. $password = "pwd";
   
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";
    
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
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2. Stack trace:
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3. #0 {main}
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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:
   
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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[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.
- i5 p4 g! J5 |- F. b+ h1 C說明: 千萬不能照它建議用"UTF8MB4",否則無法成功啟動

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  P, \, d  a1 g% ?0 i(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
  V3 _& Z" {* k7 a% ESELECT COUNT(*) FROM common_usergroup WHERE type='special' and system>0

& H8 V  y" J4 y/ ?" C. f$ 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
' [0 M: i. w) y4 F) F, S1 PSELECT * 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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第一個錯誤需要找到Discuz!目錄中的source\class\table\table_common_usergroup.php，
- j7 \' i3 o+ U$ G, V% z7 M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。

第二個錯誤需要找到Discuz!目錄下中的source\class\table\table_forum_announcement.php，
5 ?( d% O( C- M4 |8 a2 d# u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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# _2 I9 N* _1 y# G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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" F4 w+ a& i1 e1 m7 B4 }/ x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。
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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