纯手工搭建了这个“小鸟数据”博客，没有安装第三方管理面板，存取文件基本靠putty，输入指令基本靠双手，满足不了的需求则基本靠跳过。因为曾经有过误删数据库的惨痛经历，对于手工操作数据库一直是拒绝的。某天尝试了一下在Typecho中通过操作数据库的方式更新文章，就想看看数据库里有没有成功被写入，然后就很尴尬的发现自己的mysql指令就只记得一个“show databases”了。
登陆数据库
以root用户登陆，需求密码，linux的输入密码过程不会有任何的提示，如果没成功进入数据库，那估计就是密码输错了，在命令行按方向键“上”可以回溯上一条命令，再来一遍没准就输对了。
mysql -u root -p数据库一览
成功进入数据库后会出现mysql的前缀，centos8默认安装的是同源的MariaDB，前缀是“MariaDB [(none)]> ”，下面这条指令会显示所有已建立的数据库名，需要注意的是，从现在开始，末尾的分号必不可少；
show databases;进入某个库
比如博主建立了一个测试用的库“Abddb_Theme”，进入这个库可以用“use”命令,成功后命令行前缀也会被变更，变成类似下面这样的形式“MariaDB [Abddb_Theme]>”；
use Abddb_Theme;数据库有几张表？哪些字段？
typecho的数据库结构很精简，我们看一下它一共包含哪些表单，先输入：
//显示一共有几张表
show tables;
//显示表中包含的所有字段
show columns from 具体表名;利用typecho的数据库实际操作一下，顺便了解一下其字段构成；
//页面实际显示类似这样
MariaDB [Abddb_Theme]> show tables;
//程序输出如下：
+-----------------------+
| Tables_in_Abddb_Theme |
+-----------------------+
| typecho_comments |
| typecho_contents |
| typecho_fields |
| typecho_metas |
| typecho_options |
| typecho_relationships |
| typecho_users |
+-----------------------+来都来了，看下typecho表的字段吧！
comments
这张应该是放评论数据的表单；
show columns from typecho_comments;
+----------+------------------+------+-----+----------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+------------------+------+-----+----------+----------------+
| coid | int(10) unsigned | NO | PRI | NULL | auto_increment |
| cid | int(10) unsigned | YES | MUL | 0 | |
| created | int(10) unsigned | YES | MUL | 0 | |
| author | varchar(200) | YES | | NULL | |
| authorId | int(10) unsigned | YES | | 0 | |
| ownerId | int(10) unsigned | YES | | 0 | |
| mail | varchar(200) | YES | | NULL | |
| url | varchar(200) | YES | | NULL | |
| ip | varchar(64) | YES | | NULL | |
| agent | varchar(200) | YES | | NULL | |
| text | text | YES | | NULL | |
| type | varchar(16) | YES | | comment | |
| status | varchar(16) | YES | | approved | |
| parent | int(10) unsigned | YES | | 0 | |
+----------+------------------+------+-----+----------+----------------+contents
文章内容数据表单，这里的“text”字段里就放的我们文章的主体；
show columns from typecho_contents;
+--------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+------------------+------+-----+---------+----------------+
| cid | int(10) unsigned | NO | PRI | NULL | auto_increment |
| title | varchar(200) | YES | | NULL | |
| slug | varchar(200) | YES | UNI | NULL | |
| created | int(10) unsigned | YES | MUL | 0 | |
| modified | int(10) unsigned | YES | | 0 | |
| text | longtext | YES | | NULL | |
| order | int(10) unsigned | YES | | 0 | |
| authorId | int(10) unsigned | YES | | 0 | |
| template | varchar(32) | YES | | NULL | |
| type | varchar(16) | YES | | post | |
| status | varchar(16) | YES | | publish | |
| password | varchar(32) | YES | | NULL | |
| commentsNum | int(10) unsigned | YES | | 0 | |
| allowComment | char(1) | YES | | 0 | |
| allowPing | char(1) | YES | | 0 | |
| allowFeed | char(1) | YES | | 0 | |
| parent | int(10) unsigned | YES | | 0 | |
| views | int(10) | YES | | 0 | |
+--------------+------------------+------+-----+---------+----------------+fields
看了一下表里的内容，似乎是博主的一些自定义字段；
show columns from typecho_fields;
+-------------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+-------+
| cid | int(10) unsigned | NO | PRI | NULL | |
| name | varchar(200) | NO | PRI | NULL | |
| type | varchar(8) | YES | | str | |
| str_value | text | YES | | NULL | |
| int_value | int(10) | YES | MUL | 0 | |
| float_value | float | YES | MUL | 0 | |
+-------------+------------------+------+-----+---------+-------+metas
里面是一些分类以及标签的描述信息；
show columns from typecho_metas;
+-------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------------+------------------+------+-----+---------+----------------+
| mid | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(200) | YES | | NULL | |
| slug | varchar(200) | YES | MUL | NULL | |
| type | varchar(32) | NO | | NULL | |
| description | varchar(200) | YES | | NULL | |
| count | int(10) unsigned | YES | | 0 | |
| order | int(10) unsigned | YES | | 0 | |
| parent | int(10) unsigned | YES | | 0 | |
+-------------+------------------+------+-----+---------+----------------+options
这里面保存了用户的一些设置信息，不如主题用什么，有没有开启markdown;
show columns from typecho_options;
+-------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------------+------+-----+---------+-------+
| name | varchar(32) | NO | PRI | NULL | |
| user | int(10) unsigned | NO | PRI | 0 | |
| value | text | YES | | NULL | |
+-------+------------------+------+-----+---------+-------+relationships
仅两个字段的关系表，cid指的是文章的id，mid应该是目录或标签的id，这张表里存储了他们之间的从属关系；
show columns from typecho_relationships;
+-------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------------------+------+-----+---------+-------+
| cid | int(10) unsigned | NO | PRI | NULL | |
| mid | int(10) unsigned | NO | PRI | NULL | |
+-------+------------------+------+-----+---------+-------+users
用户表，这个就很容易理解了，typecho虽然小巧，也是可以支持多用户的；
show columns from typecho_users;
+------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+----------------+
| uid | int(10) unsigned | NO | PRI | NULL | auto_increment |
| name | varchar(32) | YES | UNI | NULL | |
| password | varchar(64) | YES | | NULL | |
| mail | varchar(200) | YES | UNI | NULL | |
| url | varchar(200) | YES | | NULL | |
| screenName | varchar(32) | YES | | NULL | |
| created | int(10) unsigned | YES | | 0 | |
| activated | int(10) unsigned | YES | | 0 | |
| logged | int(10) unsigned | YES | | 0 | |
| group | varchar(16) | YES | | visitor | |
| authCode | varchar(64) | YES | | NULL | |
+------------+------------------+------+-----+---------+----------------+显示所有内容
表里数据较多的时候慎用该命令，可能输出一堆数据，找到所需数据的机会如同大海捞针，找张数据较少的表演示一下吧；
select * from typecho_fields;
+-----+--------------+------+-----------+-----------+-------------+
| cid | name | type | str_value | int_value | float_value |
+-----+--------------+------+-----------+-----------+-------------+
| 14 | augPostThumb | str | | 0 | 0 |
| 15 | augPostThumb | str | | 0 | 0 |
| 16 | augPostThumb | str | | 0 | 0 |
+-----+--------------+------+-----------+-----------+-------------+限制输出的行数LIMIT
//显示前两行
select * from typecho_relationships limit 2;
+-----+-----+
| cid | mid |
+-----+-----+
| 1 | 1 |
| 1 | 13 |
+-----+-----+
//从第2行开始，显示4行（初始行号为0）
select * from typecho_relationships limit 2,4;
+-----+-----+
| cid | mid |
+-----+-----+
| 12 | 8 |
| 13 | 9 |
| 14 | 1 |
| 15 | 1 |
+-----+-----+限定条件的查找WHERE
select * from typecho_metas where mid>18;
+-----+--------+---------+----------+-------------+-------+-------+--------+
| mid | name | slug | type | description | count | order | parent |
+-----+--------+---------+----------+-------------+-------+-------+--------+
| 19 | gggg | gggg | tag | bbbbbbbbbb | 0 | 0 | 0 |
| 20 | 短篇 | short | category | NULL | 0 | 1 | 3 |
| 21 | 节选 | excerpt | category | NULL | 0 | 2 | 3 |
| 22 | 诗歌 | poem | category | NULL | 0 | 3 | 3 |
+-----+--------+---------+----------+-------------+-------+-------+--------+退出数据库
exit结语
以上命令能够对一个数据库进行简单的查询，以确认数据字段与储存的状态，至于其他更深入的用法，这里就不展开了，毕竟mysql操作内容是可以塞满整整一本书的。：）
