mysqld 升級到8以上遇到的問題

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tid=187560&(1)
; ~& R1 G4 p; W, U5 C4 h4 Y: Yphp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
) z0 o/ T, b& i3 Qmysqli_real_connect(): (HY000/2054): Server sent charset unknown to the client. Please, report to the developers
: e5 n; V+ B2 X# V3 U) \原因:
7 z  j- m1 d3 O) n) x7 b+ J- n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 t9 A( j8 U* R7 f4 O& j3 o) Ivi /etc/my.cnf  加入下列:
4 S7 p  v( |  Q3 R6 v1 N9 Q( ][mysqld]
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7 |0 U" B9 f: ~6 c8 Zcharacter-set-server=utf8
default_authentication_plugin=mysql_native_password

[mysql]
. R) c1 {" ?1 n% i! E) \default-character-set=utf8
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default-character-set=utf8
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然後重啟mysqld
service mysqld restart
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3 d  p! g  S' i+ y' w8 w( 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. <?
2. $hostname = "x.x.x.x";
3. $database = "db_name";
4. $username = "user_name";
5. $password = "pwd";
7. $conn = mysqli_connect($hostname, $username, $password,$database) or trigger_error(mysql_error(),E_USER_ERROR);
8. mysqli_query($conn ,"SET NAMES utf8");
10. $sql = "select count(*) as total from " .  "table_name";
11. $rec = mysqli_fetch_assoc(mysqli_query( $conn,$sql));
12. echo $rec['total'];
13. mysqli_close($conn);
14. ?>

複製代碼

遊客，本帖隱藏的內容需要積分高於 999999999999 才可瀏覽，您當前積分為 0

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+ _0 X* N0 B  T, D" c* B( w+ `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:
3. #0 {main}
4.   thrown in /test/connectmysql8.php on line 9
6. Fatal error: Uncaught Error: Call to undefined function mysqli_connect() in /test/connectmysql8.php:9
7. Stack trace:
8. #0 {main}
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.
說明: 千萬不能照它建議用"UTF8MB4",否則無法成功啟動

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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 'system>0' at line 1
SELECT COUNT(*) FROM common_usergroup WHERE type='special' and system>0

# w. Z0 o! L& [6 u! s(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
! P3 R5 v' e" s5 TSELECT * 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

8 W5 J& ^3 u/ N# m* s/ w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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; z0 f4 D; v2 B9 Q* a: z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。

6 z9 q+ R. g1 S6 e. p% J4 [, J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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5 o8 {" n0 q. R* C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。

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。
( `- @1 E1 ~0 Y" Y0 P; `" q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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