一、数据的导入导出
1.1数据导入导出默认路径
查看路径：
mysql> show variables like "secure_file_priv"; +------------------+-----------------------+ | Variable_name | Value | +------------------+-----------------------+ | secure_file_priv | /var/lib/mysql-files/ | +------------------+-----------------------+ 1 row in set (0.26 sec)
在MySQL登录状态下执行系统命令：在命令前加system关键字
所有导入导出的文件必须放入/var/lib/mysql-files中，不修改状态下这是默认路径
1.2修改默认路径
1)创建新的文件夹：mkdir /myload因为数据库建立时就自动生成了一个mysql的用户，这里要把这个修改路径的所有者变为mysql
chown mysql /myload
2)去数据库的配置文件中修改：
vim /etc/my.cnf
[mysqld] secure_file_priv="/myload"
3)systemctl restart mysqld 重启服务
这是再执行：show variables like "secure_file_priv"（在MySQL服务下查看），可观察到改变后的路径生效
mysql> show variables like "secure_file_priv"; +------------------+----------+ | Variable_name | Value | +------------------+----------+ | secure_file_priv | /myload/ | +------------------+----------+
1.2 数据导入：把系统文件内容存储到数据库服务器的表里(这里以把系统用户信息放入表中为例)
1） 要把将要导出的文件放入/myload中
cp /etc/passwd /myload
2）依据将要导入的文件格式在数据库中建库建表
mysql> create table db3.user( -> username char(50), -> password char(1), -> uid int, -> gid int, -> comment char(150), -> address char(50), -> shell char(50));
3）使用命令导入：
load data infile "目录名/文件名" into table 库名.表名 fields terminated "列分隔符" lines terminated "\n";
在运行上述命令格式时，出现了以下报错：
ERROR 13 (HY000): Can't get stat of '/myload/passwd' (Errcode: 13 - Permission denied)
百度后使用以下命令：load data默认读的是服务器上的文件，加上local参数后，可以实现
load data local infile "/myload/passwd " into table db3.user fields terminated by ":" lines terminated by "\n";
之后 select *from 库名.表名 即可查看到导入的信息
注意事项：—字段分隔符要与文件一致
—表字段类型和字段个数要与文件匹配
—导入数据时使用指定文件的绝对路径
1.3数据导出：
命令格式：
格式1：select into outfile "目录名/文件名"；
select *from db3.user into outfile "/myload/user1.txt";
查看：
mysql> system cat /myload/user1.txt root x 0 0 root /root /bin/bash bin x 1 1 bin /bin /sbin/nologin daemon x 2 2 daemon /sbin /sbin/nologin adm x 3 4 adm /var/adm /sbin/nologin lp x 4 7 lp /var/spool/lpd /sbin/nologin sync x 5 0 sync /sbin /bin/sync shutdown x 6 0 shutdown /sbin /sbin/shutdown halt x 7 0 halt /sbin /sbin/halt mail x 8 12 mail /var/spool/mail /sbin/nologin operator x 11 0 operator /root /sbin/nologin games x 12 100 games /usr/games /sbin/nologin ftp x 14 50 FTP User /var/ftp /sbin/nologin nobody x 99 99 Nobody / /sbin/nologin
格式2：select into outfile "目录名/文件名" fields terminated by "分隔符"；
mysql> select *from db3.user into outfile "/myload/user2.txt" fields terminated by ":"; ##指明列与列之间增加：
查看：
mysql> system cat /myload/user2.txt root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin
格式3：select into outfile "目录名/文件名" fields terminated by "分隔符" lines terminated by "\n";
mysql> select *from db3.user into outfile "/myload/user3.txt" fields terminated by ":" lines terminated by "\n"; ###结果和格式2 没有区别
mysql> system cat /myload/user3.txt root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin adm:x:3:4:adm:/var/adm:/sbin/nologin lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin
注意事项：
—导出的数据行数由sql查询决定
—导出的是表记录，不包括字段名（只是表中的数据）
—自动创建存储数据的文件（指定名字就好，不必实现创建）
—存储数据文件，具有唯一性
导入过程中一直报错Can't create/write to file '/myload/user1.txt' (Errcode: 13 - Permission denied)找了半天才发现是SElinux没有关（心累ing上面的local可能也是这个原因）
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二、管理表记录
mysql> select *from T3; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | bob | | 19 | music | 67 | | lucy | 3 | 19 | music | 78 | | anmy | 2 | 19 | music | 91 | | lili | 1 | 19 | music | 86 | +------+-------+------+-------+--------+
2.1增加表记录
1）增加一条记录，给所有字段赋值
这种情况下，不需要明确指出字段，但每条记录的值的顺序、类型都必须与表格结构向一致，否则可能无法正确插入记录。
insert into T3 values("kangkang",1,16,eat,60);
2）给指定字段赋值
这种情况下，必须指出各项值所对应的字段；而且，未赋值的字段应设置有默认值或者有自增填充属性或者允许为空，否则插入操作将会失败。
mysql> insert into T3(name,class,grades) values("lulu",2,78);
当然也可以插多条表记录，逗号隔开。
2.2更新记录表
1）更新表记录时，若未限制条件，则适用于所有记录
mysql> update T3 set age=18;
mysql> select *from T3; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | bob | | 18 | music | 67 | | lucy | 3 | 18 | music | 78 | | anmy | 2 | 18 | music | 91 | | lili | 1 | 18 | music | 86 | | kangkang | 1 | 18 | eat | 60 | | lulu | 2 | 18 | music | 78 | +----------+-------+------+-------+--------+
2）可以限制条件：
mysql> update T3 set age=24 where name="lili"; ####where指定限制条件
mysql> select *from T3; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | bob | | 18 | music | 67 | | lucy | 3 | 18 | music | 78 | | anmy | 2 | 18 | music | 91 | | lili | 1 | 24 | music | 86 | | kangkang | 1 | 18 | eat | 60 | | lulu | 2 | 18 | music | 78 | +----------+-------+------+-------+--------+
删除的时候也可以限定条件：mysql> delete from T3 where age=24;
mysql> select *from T3; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | bob | | 18 | music | 67 | | lucy | 3 | 18 | music | 78 | | anmy | 2 | 18 | music | 91 | | kangkang | 1 | 18 | eat | 60 | | lulu | 2 | 18 | music | 78 | +----------+-------+------+-------+--------+
2.3查询记录表select
1）select *from 库名.表名; ###查询表的所有数据内容
2）select 字段名，字段名 from 库名.表名 ；####查固定字段
mysql> select name ,likes from T3; +----------+-------+ | name | likes | +----------+-------+ | bob | music | | lucy | music | | anmy | music | | kangkang | eat | | lulu | music | +----------+-------+
3）与where条件限制连用
select */字段名，字段名 from 表名 where 限制条件
mysql> select name,class,age from T3 where grades=78; +------+-------+------+ | name | class | age | +------+-------+------+ | lucy | 3 | 18 | | lulu | 2 | 18 | +------+-------+------+ 2 rows in set (0.00 sec) mysql> select * from T3 where grades=78; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lucy | 3 | 18 | music | 78 | | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+ 2 rows in set (0.00 sec)
— *代表所有字段
—查看当前库表时，库名可以省略
—指定的字段是列
—指定的条件限制是行
3、匹配条件
3.1聚集函数
count 字段名 统计字段值的个数
mysql> select count(name)from T3; +-------------+ | count(name) | +-------------+ | 5 | +-------------+
sum 字段名 统计字段总和
max 字段名 字段值最大
min 字段名 字段值最小
avg 字段名 字段值的平均值
mysql> select sum(age),avg(grades),max(grades),min(grades)from T3; +----------+-------------+-------------+-------------+ | sum(age) | avg(grades) | max(grades) | min(grades) | +----------+-------------+-------------+-------------+ | 90 | 74.8000 | 91 | 60 | +----------+-------------+-------------+-------------+
可以与where连用
3.2普通匹配条件
1、数值比较（字段类型必须是数值类型）
> < = >= <= ！=
ysql> select * from T3 where age>18 and grades>70; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lucy | 3 | 24 | music | 78 | +------+-------+------+-------+--------+ 1 row in set (0.00 sec)
2、字符比较/匹配空/匹配非空（字段类型必须为字符型）
= ！= is null is not null
3、逻辑匹配（多个判断条件时使用）
and(逻辑与) or（逻辑或） ！ not(逻辑非)
4、范围匹配/去重显示
（匹配范围内的任意一个值）
in（在……里） not in (不在……里) between……and (在……之间) distinct （去重显示）
mysql> select *from T3 where name in ('bob','lili','fangfang'); +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | bob | | 18 | music | 67 | +------+-------+------+-------+--------+
3.3高级匹配
1）模糊查询
where 字段 like '通配符'，not like 可以显示不以……的
通配符： %表示0~n个字符
_表示一个字符
可以把通配符放在不同的位置来作为匹配
mysql> select *from T3 where name like "l%"; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lucy | 3 | 24 | music | 78 | | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+ 2 rows in set (0.00 sec) mysql> select *from T3 where name like "l_l_"; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+
2）正则表达式regexp
where 字段 regexp '正则表达式'
正则表达式符号：^ （开头）$（结尾） .（英文中.表示一个字节，中文...表示一个汉字） | *
###查询姓名以 l 开头或 y 结尾的
mysql> select * from T3 where name regexp '^l|y$'; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lucy | 3 | 24 | music | 78 | | anmy | 2 | 18 | music | 91 | | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+
mysql> select * from T3 where name regexp '.u'; ####找姓名中的u前面一个是字符的 +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lucy | 3 | 24 | music | 78 | | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+
找到 字母 l 和字母 l 之间还有一个字符的姓名
mysql> select *from T3; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | bob | | 18 | music | 67 | | lucy | 3 | 24 | music | 78 | | anmy | 2 | 18 | music | 91 | | kangkang | 1 | 18 | eat | 60 | | lulu | 2 | 18 | music | 78 | | llu | 2 | 17 | game | 88 | | luul | 2 | 21 | game | 98 | +----------+-------+------+-------+--------+ 7 rows in set (0.00 sec) mysql> select * from T3 where name regexp 'l.l'; +------+-------+------+-------+--------+ | name | class | age | likes | grades | +------+-------+------+-------+--------+ | lulu | 2 | 18 | music | 78 | +------+-------+------+-------+--------+
3）四则运算
+ - * / % （）提高优先级
）使用SELECT做数学计算 计算1234与5678的和： mysql> SELECT 1234+5678; +-----------+ | 1234+5678 | +-----------+ | 6912 | +-----------+ 1 row in set (0.00 sec) 计算1234与5678的乘积： mysql> SELECT 1234*5678; +-----------+ | 1234*5678 | +-----------+ | 7006652 | +-----------+ 1 row in set (0.00 sec) 计算1.23456789除以3的结果： mysql> SELECT 1.23456789/3; +----------------+ | 1.23456789/3 | +----------------+ | 0.411522630000 | +----------------+ 1 row in set (0.00 sec) 输出stu_info表各学员的姓名、15年后的年龄： mysql> SELECT name,age+15 FROM stu_info; +-------+--------+ | name | age+15 | +-------+--------+ | Jim | 39 | | Tom | 36 | | Lily | 35 | | Jerry | 42 | | Mike | 36 | +-------+--------+ 5 rows in set (0.00 sec)
4）查询结果排序（通常都是数值类型的字段）
sql 查询 order by 字段名 [asc | desc ];
---asc 升序排列
—desc 降序排列
ysql> select * from T3 order by grades asc; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | kangkang | 1 | 18 | eat | 60 | | bob | | 18 | music | 67 | | lucy | 3 | 24 | music | 78 | | lulu | 2 | 18 | music | 78 | | llu | 2 | 17 | game | 88 | | anmy | 2 | 18 | music | 91 | | luul | 2 | 21 | game | 98 | +----------+-------+------+-------+--------+
5）限制查询结果的输出条数，LIMIT
mysql> select * from T3 order by grades asc limit 4; +----------+-------+------+-------+--------+ | name | class | age | likes | grades | +----------+-------+------+-------+--------+ | kangkang | 1 | 18 | eat | 60 | | bob | | 18 | music | 67 | | lucy | 3 | 24 | music | 78 | | lulu | 2 | 18 | music | 78 | +----------+-------+------+-------+--------+ 4 rows in set (0.00 sec)
6）分组查询结果，GROUP BY（通常都是字符类型）
mysql> select likes,count(likes) from T3 group by likes; +-------+--------------+ | likes | count(likes) | +-------+--------------+ | music | 4 | | game | 2 | | eat | 1 | +-------+--------------+ 3 rows in set (0.00 sec)
7）AS指定别名
mysql> select name as "姓名" from T3; +----------+ | 姓名 | +----------+ | anmy | | bob | | kangkang | | llu | | lucy | | lulu | | luul | +----------+
总结：所有想要在屏幕上显示的内容都可以在select后指定
8）条件过滤： having
mysql> select name from T3 where grades>78 having name="llu"; +------+ | name | +------+ | llu | +------+
聚合函数不可以与where连用，但是可以与having连用，having常与group by 连用
如查找平均分超过80分的班级，并显示班级和平均分
mysql> select class,avg(grades)from T3 group by class having avg(grades>80); +-------+-------------+ | class | avg(grades) | +-------+-------------+ | 2 | 88.7500 | +-------+-------------+ 1 row in set (0.00 sec)
4.MySQL的管理方式
部署LAMP+phpMyAdmin平台
步骤一：准备软件的运行环境 lamp
- [root@mysql6~]# rpm -q httpd php php-mysql //检测是否安装软件包
- 未安装软件包 httpd
- 未安装软件包 php
- 未安装软件包 php-mysql
- [root@mysql6~]# yum -y install httpd php php-mysql //装包
- [root@mysql6~]# systemctl start httpd //启动服务
- [root@mysql6~]# systemctl enable httpd //设置开机自启
- Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.
步骤二：测试运行环境
- [root@mysql6~]# vim /var/www/html/test.php //编辑页面测试文件
- [root@mysql6~]# cat /var/www/html/test.php //查看页面测试文件
- <?php
- $x=mysql_connect("localhost","root","123456");
- if($x){ echo "ok"; }else{ echo "no"; };
- ?>
- [root@mysql6~]# yum -y install elinks //安装测试网页工具
- [root@mysql6~]# elinks --dump http://localhost/test.php
- Ok //验证测试页面成功
步骤三：安装软件包
1）物理机传输解压包给虚拟机192.168.4.6
- [root@room9pc桌面]# scp phpMyAdmin-2.11.11-all-languages.tar.gz 192.168.4.6:/root/
- root@192.168.4.6's password:
- phpMyAdmin-2.11.11-a 100% 4218KB 122.5MB/s 00:00
2）虚拟机192.168.4.6解压phpMyAdmin-2.11.11-all-languages.tar.gz压缩包
- [root@mysql6~]# tar -zxf phpMyAdmin-2.11.11-all-languages.tar.gz -C /var/www/html/ //-C 表示改变至目录
- [root@mysql6~]# cd /var/www/html/
- [root@mysql6~]# mv phpMyAdmin-2.11.11-all-languages phpmyadmin //改变目录名
- [root@mysql6~]# chown -R apache:apache phpmyadmin/ //改变phpmyadmin目录权限
步骤四：修改软件的配置文件定义管理的数据库服务器
切换到部署后的phpmyadmin程序目录，拷贝配置文件，并修改配置以正确指定MySQL服务器的地址
- [root@mysql6html]# cd phpmyadmin
- [root@mysql6 phpmyadmin]# cp config.sample.inc.php config.inc.php
- //备份主配置文件
- [root@mysql6 phpmyadmin]# vim config.inc.php //编辑主配置文件
- 17 $cfg['blowfish_secret'] = 'plj123'; //给cookie做认证的值，可以随便填写
- 31 $cfg['Servers'][$i]['host'] = 'localhost'; //指定主机名，定义连接哪台服务器
- :wq
步骤五：在客户端访问软件 管理数据库服务器
1）在客户端访问软件,打开浏览器输入http://192.168.4.6/phpmyadmin(数据库服务器地址) 访问软件，如图-1所示，用户名是root，密码是123456
图-1
2）登入成功后，如图-2示，即可在授权范围内对MySQL数据库进行管理。