MYSQL数据库Mysql help命令（帮助信息）中文注解

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MYSQL必读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.

MYSQL必读1)MySQL官方手册

MYSQL必读和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.

MYSQL必读下载位置：http://dev.mysql.com/doc/

MYSQL必读2)MySQL客户端工具自带的帮助

MYSQL必读
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> help
For 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mysql
go    (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 names
You can turn off this feature to get a quicker startup with -A
Connection id:  5
Current 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,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spool
Logging to file '/tmp/query.log'
mysql> select table_name,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 off
Outfile 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 chardb
select * from tb_isam;
mysql> source query.sql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database 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 5.1
Connection id:     6
Current database:    chardb
Current user:      root@localhost
SSL:          Not in use
Current pager:     less
Using outfile:     ''
Using delimiter:    ;
Server version:     5.5.37-log MySQL Community Server (GPL)
Protocol version:    10
Connection:       Localhost via UNIX socket
Server characterset:  latin1
Db   characterset:  utf8
Client characterset:  latin1
Conn. characterset:  latin1
UNIX socket:      /var/lib/mysql/mysql.sock
Uptime:         3 hours 10 min 59 sec
Threads: 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 changed
mysql> s
--------------
mysql Ver 14.14 Distrib 5.5.37,for Linux (x86_64) using readline 5.1
Connection id:     6
Current database:    chardb
Current user:      root@localhost
SSL:          Not in use
Current pager:     less
Using outfile:     ''
Using delimiter:    ;
Server version:     5.5.37-log MySQL Community Server (GPL)
Protocol version:    10
Connection:       Localhost via UNIX socket
Server characterset:  latin1
Db   characterset:  utf8
Client characterset:  gbk   ---客户端和conn端字符集都变成gbk了.
Conn. characterset:  gbk
UNIX socket:      /var/lib/mysql/mysql.sock
Uptime:         3 hours 13 min 33 sec
Threads: 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 1
mysql> 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.

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