mysqld 升級到8以上遇到的問題

coav4u

(1)
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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mysqli_real_connect(): Server sent charset (255) unknown to the client. Please, report to the developers
5 D$ P2 k3 o: n: h6 Omysqli_real_connect(): (HY000/2054): Server sent charset unknown to the client. Please, report to the developers
* f* F$ N1 b4 m# T% ^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:
6 f9 K0 z  v& K+ \& Qvi /etc/my.cnf  加入下列:
[mysqld]

4 h) n# P; S( `character-set-server=utf8
9 `+ i* j4 Y% T/ M) p1 g2 Xdefault_authentication_plugin=mysql_native_password
, W4 j, u/ G: ]9 Svalidate_password.policy=LOW
[mysql]
$ A: q& o. P/ X/ Xdefault-character-set=utf8

% X! n9 ~! K5 h' R! p% j  ^[client]
default-character-set=utf8

( f; y0 l" f. c/ O" S6 M0 y然後重啟mysqld
1 _8 |5 G! ^+ u! c2 `) M' Hservice mysqld restart

, P, ~5 g# l% i, D! J( M重啟後可能須做下列動作:
2 x6 p0 E+ [8 l) H0 `& Hmysql -u roor -p  
- [  u& A8 V- [1 B! |$ GSHOW 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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& @5 S$ y$ k' m2 d9 q: @3 Z" D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";
   
3. $database = "db_name";
   
4. $username = "user_name";
   
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);
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8. mysqli_query($conn ,"SET NAMES utf8");
   
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 $rec['total'];
    : |/ K: x6 N# }3 }
13. mysqli_close($conn);
    
14. ?>

複製代碼

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6 E+ @, h$ Y& R, e: z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}
   
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.
6 y$ a5 H5 K% M7 ~+ ^: ?說明: 千萬不能照它建議用"UTF8MB4",否則無法成功啟動

$ t" h: O7 A0 m3 b, K(2)
8 `9 n) ^% @4 v5 Y3 x& |(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
3 W7 l/ q# Z7 ]2 ^/ YSELECT COUNT(*) FROM common_usergroup WHERE type='special' and system>0
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4 t9 ~$ }# {: Y( i/ P6 Y(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
6 ^7 X$ e1 U) s! u. BSELECT * 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

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`。

, P  N) c" g* N5 @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。

2 k1 t: k, k5 [4 I: F6 f& x- z  `' `5 B第二個錯誤需要找到Discuz!目錄下中的source\class\table\table_forum_announcement.php，
& _+ t# B. c) I0 V+ l8 |, e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。

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。

, D( u5 {/ E1 ~3 C, s9 |7 M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。
! J% O, }) x1 B9 J8 F0 K' b+ i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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