問題描述：
PHP message: WordPress數據庫 xxx… 發生 Lost connection to MySQL server during query錯誤，這是由 xxx ….。
其他表現，訪問網頁時提示： 建立數據庫連接時出錯 。
問題原因：
通常是因為數據庫軟件跟數據庫本身版本不匹配導致，比如數據庫軟件升級，或者數據庫遷移，這時候，某些表結構發生變化，從而導致訪問數據庫出錯。
打開/var/lib/mysql/xxx.err文件，通常會發現如下內容：
[ERROR] mysqld: Table './dbname/wp_options' is marked as crashed and should be repaired [Warning] Checking table: './dbname/wp_options' [ERROR] mysqld: Table './dbname/wp_users' is marked as crashed and should be repaired [Warning] Checking table: './dbname/wp_users' 。。。。。
解決方案：
解決方案通常是通過mysql_upgrade檢查修複數據庫中的表。示例如下：
[root@vimsky ~]# mysql_upgrade -u root -p
Enter password:
Phase 1/4: Fixing views
Phase 2/4: Fixing table and database names
Phase 3/4: Checking and upgrading tables Processing databases information_schema mywordpressblogsDB
mywordpressblogsDB.wp_commentmeta OK
mywordpressblogsDB.wp_comments OK
mywordpressblogsDB.wp_cptch_images OK
mywordpressblogsDB.wp_cptch_packages OK
mywordpressblogsDB.wp_cptch_whitelist OK
mywordpressblogsDB.wp_gravatars OK
mywordpressblogsDB.wp_links OK
mywordpressblogsDB.wp_options OK
mywordpressblogsDB.wp_postmeta OK
mywordpressblogsDB.wp_posts OK
mywordpressblogsDB.wp_supsystic_tbl_columns OK
mywordpressblogsDB.wp_supsystic_tbl_diagrams OK
mywordpressblogsDB.wp_supsystic_tbl_rows OK
mywordpressblogsDB.wp_supsystic_tbl_tables OK
mywordpressblogsDB.wp_term_relationships OK
mywordpressblogsDB.wp_term_taxonomy OK
mywordpressblogsDB.wp_termmeta OK
mywordpressblogsDB.wp_terms OK
mywordpressblogsDB.wp_usermeta OK
mywordpressblogsDB.wp_users OK
mywordpressblogsDB.wp_wp_rp_tags OK
mysql mysql.columns_priv OK
mysql.db OK
mysql.event OK
mysql.func OK
mysql.help_category OK
mysql.help_keyword OK
mysql.help_relation OK
mysql.help_topic OK
mysql.host OK
mysql.ndb_binlog_index OK
mysql.plugin OK
mysql.proc OK
mysql.procs_priv OK
mysql.proxies_priv OK
mysql.servers OK
mysql.tables_priv OK
mysql.time_zone OK
mysql.time_zone_leap_second OK
mysql.time_zone_name OK
mysql.time_zone_transition OK
mysql.time_zone_transition_type OK
mysql.user OK
performance_schema test Phase 4/4: Running 'mysql_fix_privilege_tables' OK
[root@vimsky ~]#