在开发或测试环境在碰到mysql相关故障时，大多数朋友可能会通过论坛发帖，QQ群讨论方式来获取帮助。该方式是获取帮助的有效途径之一。然而如果在生产环境，在没有网络的环境下，这些方式就无助于问题的解决。无论何种数据库，从官方网站获取帮助是最直接最有效的方式。其次没有网络的环境下，我们可以通过MySQL客户端工具自带的帮助信息来解决问题。
1)MySQL官方手册
和Oracle官方文档一下，MySQL官方手册是获取MySQL帮助最直接最效的方式。该手册包含很多个部分，比如有关SQL的语法，MySQL安装方式，MySQL的系统变量，状态变量，命令行的常用工具，数据库的管等等。总之是一个MySQL数据相关的大合集。支持PDF及html方式下载。
下载位置：http://dev.mysql.com/doc/
2)MySQL客户端工具自带的帮助
| 获取mysql有关的帮助信息，直接在mysql提示符下输入help即可获得有关在mysql客户端相关的帮助信息。这个方式与Oracle SQL*plus下的help 是类似的。mysql> helpFor information about MySQL products and services, visit: http://www.mysql.com/For developer information, including the MySQL Reference Manual, visit: http://dev.mysql.com/To buy MySQL Enterprise support, training, or other products, visit: https://shop.mysql.com/List of all MySQL commands:Note that all text commands must be first on line and end with ';' ? (/?) Synonym for `help'. clear (/c) Clear the current input statement. --清除当前输入的语句connect (/r) Reconnect to the server. Optional arguments are db and host. --重新连接，通常用于被剔除或异常断开后重新连接，SQL*plus下也有这样一个connect命令delimiter (/d) Set statement delimiter. --设置命令终止符，缺省为；，比如我们可以设定为/来表示语句结束 edit (/e) Edit command with $EDITOR. --编辑缓冲区的上一条SQL语句到文件，缺省调用vi，文件会放在/tmp路径下ego (/G) Send command to mysql server, display result vertically. --控制结果显示为垂直显示exit (/q) Exit mysql. Same as quit. --退出mysqlgo (/g) Send command to mysql server. --发送命令到mysql服务help (/h) Display this help.nopager (/n) Disable pager, print to stdout. --关闭页设置，打印到标准输出 notee (/t) Don't write into outfile. --关闭输出到文件pager (/P) Set PAGER [to_pager]. Print the query results via PAGER. --设置pager方式，可以设置为调用more,less等等，主要是用于分页显示print (/p) Print current command. prompt (/R) Change your mysql prompt. --改变mysql的提示符 quit (/q) Quit mysql. rehash (/#) Rebuild completion hash. --自动补齐相关对象名字 source (/.) Execute an SQL script file. Takes a file name as an argument. --执行脚本文件status (/s) Get status information from the server. --获得状态信息system (/!) Execute a system shell command. --执行系统命令 tee (/T) Set outfile [to_outfile]. Append everything into given outfile.--操作结果输出到文件 use (/u) Use another database. Takes database name as argument. --切换数据库charset (/C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets. --设置字符集warnings (/W) Show warnings after every statement. --打印警告信息nowarning (/w) Don't show warnings after every statement.--上面的所有命令，扩号内的为快捷操作，即只需要输入“/”+ 字母即可执行For server side help, type 'help contents' --注意这里的描述help contents将获得服务器端的相关帮助信息--演示部分，演示常用命令--connect命令mysql> connect chardb localhost;Reading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -AConnection id: 5Current database: chardb--设置分页，在多余一个页面显示时会不停的翻滚，用该命令可以设置分页，设置为调用系统命令mysql> pager more --设置为more方式PAGER set to 'more'mysql> select table_name,table_type,engine from information_schema.tables; --该查询会超出一屏显示后按空格键会自动翻滚到下一屏mysql> pager tail -5; --设置输出尾部5行PAGER set to 'tail -5'mysql> select table_name,table_type,engine from information_schema.tables;| setup_timers | BASE TABLE | PERFORMANCE_SCHEMA || threads | BASE TABLE | PERFORMANCE_SCHEMA || animals | BASE TABLE | InnoDB || shop | BASE TABLE | InnoDB |+----------------------------------------------+-------------+--------------------+92 rows in set (0.02 sec)mysql> pager; --查看当前的pager设置PAGER set to 'tail -5'mysql> nopager; --切换到标准(缺省)pager方式PAGER set to stdout--tee命令，输出日志文件mysql> tee /tmp/query.log --开启输出到文件，相当与SQL*plus下的spoolLogging to file '/tmp/query.log'mysql> select table_name,table_type,engine from information_schema.tables;+----------------------------------------------+-------------+--------------------+| table_name | table_type | engine |+----------------------------------------------+-------------+--------------------+| CHARACTER_SETS | SYSTEM VIEW | MEMORY || COLLATIONS | SYSTEM VIEW | MEMORY | .............mysql> notee; --关闭输出到文件，相当于SQL*Plus下的spool offOutfile disabled.mysql> system tail /tmp/query.log --查看输出的日志文件| setup_consumers | BASE TABLE | PERFORMANCE_SCHEMA || setup_instruments | BASE TABLE | PERFORMANCE_SCHEMA || setup_timers | BASE TABLE | PERFORMANCE_SCHEMA || threads | BASE TABLE | PERFORMANCE_SCHEMA || animals | BASE TABLE | InnoDB || shop | BASE TABLE | InnoDB |+----------------------------------------------+-------------+--------------------+92 rows in set (0.02 sec) --改变mysql提示符mysql> prompt SessionA> PROMPT set to 'SessionA> '--恢复到缺省提示符SessionA> prompt;Returning to default PROMPT of mysql> --执行sql脚本文件mysql> system more query.sql --注意，此时为当前目录use chardbselect * from tb_isam;mysql> source query.sqlReading table information for completion of table and column namesYou can turn off this feature to get a quicker startup with -ADatabase changed+------+-------+| id | value |+------+-------+| 1 | a || 2 | b || 3 | c || 4 | f |+------+-------+4 rows in set (0.00 sec)--获取状态信息mysql> status;--------------mysql Ver 14.14 Distrib 5.5.37, for Linux (x86_64) using readline 5.1Connection id: 6Current database: chardbCurrent user: root@localhostSSL: Not in useCurrent pager: lessUsing outfile: ''Using delimiter: ;Server version: 5.5.37-log MySQL Community Server (GPL)Protocol version: 10Connection: Localhost via UNIX socketServer characterset: latin1Db characterset: utf8Client characterset: latin1Conn. characterset: latin1UNIX socket: /var/lib/mysql/mysql.sockUptime: 3 hours 10 min 59 secThreads: 1 Questions: 97 Slow queries: 0 Opens: 313 Flush tables: 1 Open tables: 51 Queries per second avg: 0.008----------------修改客户端字符集mysql> charset gbk;Charset changedmysql> /s--------------mysql Ver 14.14 Distrib 5.5.37, for Linux (x86_64) using readline 5.1Connection id: 6Current database: chardbCurrent user: root@localhostSSL: Not in useCurrent pager: lessUsing outfile: ''Using delimiter: ;Server version: 5.5.37-log MySQL Community Server (GPL)Protocol version: 10Connection: Localhost via UNIX socketServer characterset: latin1Db characterset: utf8Client characterset: gbk ---客户端和conn端字符集都变成gbk了。Conn. characterset: gbkUNIX socket: /var/lib/mysql/mysql.sockUptime: 3 hours 13 min 33 secThreads: 1 Questions: 105 Slow queries: 0 Opens: 313 Flush tables: 1 Open tables: 51 Queries per second avg: 0.009--------------mysql> warnings;Show warnings enabled.mysql> selecs 1;ERROR 1064 (42000): 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 'selecs 1' at line 1mysql> show warnings;+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+| Level | Code | Message |+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+| Error | 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 'selecs 1' at line 1 |+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)mysql> show errors;+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+| Level | Code | Message |+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+| Error | 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 'selecs 1' at line 1 |+-------+------+------------------------------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec)mysql> nowarning;Show warnings disabled. |
