mysql数据导入导出:
导入:
把系统的文件的内容,保存到数据库的表里
导入数据的基本格式:
mysql> load data infile "文件名" into table 表名 fields terminated by ‘分隔符‘ lines terminated by ‘\n‘;
实例:把系统用户信息保存到hydra01库下的userinfo表里
mysql> create table userinfo(name char(20),password char(1),uid int(2),gid int(2),comment varchar(50),homedir varchar(60),shell varchar(25),index(name));
mysql> load data infile "/etc/passwd" into table hydra01.userinfo fields terminated by ":" lines terminated by ‘\n‘;(导入数据)
mysql> alter table userinfo add id int(2) auto_increment primary key first;(添加编号)
mysql> desc userinfo;
+----------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+----------------+
| id | int(2) | NO | PRI | NULL | auto_increment |
| name | char(20) | YES | MUL | NULL | |
| password | char(1) | YES | | NULL | |
| uid | int(2) | YES | | NULL | |
| gid | int(2) | YES | | NULL | |
| comment | varchar(50) | YES | | NULL | |
| homedir | varchar(60) | YES | | NULL | |
| shell | varchar(25) | YES | | NULL | |
+----------+-------------+------+-----+---------+----------------+
导出:
把数据库中表里的记录存储到系统文件里
导出数据的基本格式:
格式一:mysql> select * from 库.表 into outfile "文件名";
格式二:mysql> select * from 库.表 into outfile "文件名" fields terminated by "符号";
实例:把mysql库下user表里的所有记录保存到系统文件xx.txt里
mysql> select * from mysql.user into outfile "xx.txt";
[[email protected] ~]# find / -name "xx.txt"
/var/lib/mysql/xx.txt(导出的内容默认存放在mysql下)
也可以导出到指定目录下
[[email protected] ~]# mkdir mysqldata
[[email protected] ~]# chown mysql /root/mysqldata(更改属主)
mysql> select * from mysql.user into outfile "/root/mysqldata/xx2.txt";
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管理表记录
向表中插入新记录
一次向表中插入一条新记录,给新记录的每个字段都赋值
格式:mysql> insert into 库名.表名 values(字段值列表);
实例:给hydra01库的userinfo表插入一条新信息
mysql> insert into hydra01.userinfo values(26,"hydra","x",2003,20003,"hail hydra","/home/hydra","/bin/bash");
一次向表中插入多条新记录,给新记录的每个字段都赋值
格式:mysql> insert into 库名.表名 values(字段值列表),values(字段值列表),(字段值列表);
实例:给hydra01库的userinfo表插入多条新信息
mysql> insert into hydra01.userinfo values(29,"FBI","x",1937,1937,"hail hydra","/home/hydra","/bin/bash"),(30,"CIA","x",1937,1937,"hail hydra","/home/hydra","/bin/bash");
一次向表中插入多条新记录,给新记录的指定字段赋值
格式:mysql> insert into 库名.表名(字段名列表) values(字段值列表);
实例:给hydra01库的userinfo表插入新信息,并只给指定字段赋值
mysql> insert into hydra01.userinfo(name,password,uid,gid,comment,homedir,shell)values("Anonymousx","x",1937,1937,"teacher","/home/Anonymousx","/sbin/nogin");
查看效果
mysql> select * from userinfo;
+----+------------+----------+------+-------+------------------------------+---------------------+----------------+
| 26 | hydra | x | 2003 | 20003 | hail hydra | /home/hydra | /bin/bash |
| 27 | FBI | x | 2003 | 2003 | hail hydra | /home/hydra | /bin/bash |
| 28 | CIA | x | 2003 | 2003 | hail hydra | /home/hydra | /bin/bash |
| 29 | FBI | x | 1937 | 1937 | hail hydra | /home/hydra | /bin/bash |
| 30 | CIA | x | 1937 | 1937 | hail hydra | /home/hydra | /bin/bash |
| 31 | Anonymous | NULL | NULL | NULL | NULL | NULL | NULL |
| 32 | Anonymousx | x | 1937 | 1937 | teacher | /home/Anonymousx | /sbin/nogin |
+----+------------+----------+------+-------+------------------------------+---------------------+----------------+
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查询表
格式:
select 字段名列表 from 库名.表名 where 条件;
条件的表示方式:
数值比较:
条件格式:字段名 符号 数值
= != < > <= >=
实例:mysql> select * from userinfo where id <=10;
字符比较:
条件格式:字段名 符号 "值"
= != "
实例:mysql> select * from userinfo where shell!="sbin/nologin";
范围匹配:
条件格式:字段名 符号 匹配
between..adn.. /在..之间
in (值列表) /在里面
not in(值列表) /不在里面
实例:mysql> select * from userinfo where uid between 10 and 20;
逻辑匹配:
条件格式:字段名 符号 匹配 (多个查询条件时使用)
and:多个条件同时匹配
or:多个条件,匹配某一条件就可以
!:取反
实例:mysql> select * from userinfo where name="mysql" or uid=3000 ;
匹配空:
条件格式:字段名 符号 匹配
is null
实例:mysql> select * from userinfo where name is null;
匹配非空:
条件格式:字段名 符号 匹配
is not null
实例:mysql> select * from userinfo where name is not null;
模糊查询:
条件格式:字段名 like ‘表达式‘
%:匹配0个或多个字符
_:匹配任意一个字符
实例:mysql> select * from userinfo where name like ‘____‘;
正则匹配:
条件格式:字段名 regexp ‘正则表达式‘
^:开头
$:结尾
.:任意字符
*:任意字符
[]:区间
实例:mysql> select * from userinfo where uid regexp ‘[0-100]‘;
数学计算:
条件格式:字段名 计算 as 起名字 from 计算的表;
+ - * / %(取于)
实例:mysql> select uid,gid,(uid+gid)/2 as zhi from userinfo;
聚集函数:
条件格式:select xxx(字段名) from 表;
max(字段名)求最大值
min(字段名)求最小值
avg(字段名)求评价值
sum(字段名)求和
count(字段名)统计值个数
实例:mysql> select max(uid) from userinfo;
给查询结果排序:
格式:order by 字段名 排序方式;
排序方式:
asc:升序(默认排序方式)
desc:降序
实例:mysql> select name,uid from userinfo where uid >=10 and uid <=50 order by uid desc;
给查询结果分组:
格式:group by 字段名
实例: mysql> select shell from userinfo where uid <=10 group by shell;
限制显示查询结果显示的记录数inmit:
格式:limit 行数;
实例:mysql> select name,uid from userinfo where uid <=8 limit 2;
综合测试:
1.输出userinfo表中uid号最大的用户信息
测试:mysql> select * from userinfo order by uid desc limit 1;
2.输出表中uid号是两位数的最大的用户名和uid号
测试:mysql> select name,uid from userinfo where uid regexp ‘^..$‘ order by uid desc limit 1;
查看表中符合条件的记录,【所有】字段的值
格式:mysql> select * from 库名.表名 wher 条件;
实例:
mysql> select * from userinfo where id <=10;(数值比较)
mysql> select * from userinfo where shell!="sbin/nologin";(字符比较)
mysql> select * from userinfo where uid between 10 and 20;(范围匹配)
mysql> select * from userinfo where uid in (5,15,25);(范围匹配)
mysql> select * from userinfo where name in ("apache","mysql");(范围匹配)
mysql> select * from userinfo where name not in ("apache","mysql");(范围匹配)
mysql> select * from userinfo where name regexp ‘[0-9]‘;(正则)
查看表中符合条件记录,【指定】字段的值
格式:mysql> select 指定字段 from 库名.表名 wher 条件;
实例:
mysql> select id from userinfo where id <=10;(数值比较)
mysql> select name from userinfo where shell="sbin/nologin";(字符比较)
mysql> select name,id from userinfo where uid between 10 and 20;(范围匹配)
mysql> select name from userinfo where name="mysql" and uid=3000 ;(逻辑匹配)
mysql> select name from userinfo where name="mysql" or uid=3000 ;(逻辑匹配)
mysql> select name from userinfo where name is null;(匹配空)
mysql> select name from userinfo where name is not null;(匹配非空)
mysql> select name from userinfo where name like ‘____‘;(模糊查询)
mysql> select max(uid) from userinfo;(聚集函数)
mysql> select uid,gid,(uid+gid)/2 as zhi from userinfo;(数学计算)
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嵌套查询:把内层查询结果作为外层查询的查询条件。
格式:where 条件(子查询);
实例:把userinfo表中uid字段的值小于次字段平均值的用户名和uid号显示出来
测试:mysql> select name,uid from userinfo where uid < (select avg(uid) from userinfo);
实例:嵌套查询可以跨库查询
测试:mysql> select name from userinfo where name in (select user from mysql.user where user="root" and host="localhost");
复制表:(原表的索引不会被复制)
格式:create table 新名字 select * from 被复制的表
测试:mysql> create table userinfox select * from userinfo;
实例:复制userinfo表的前十条
测试;mysql> create table userinfox1 select * from userinfo limit 10;
复制表结构:(复制表结构不会复制数据)
格式:格式:create table 新名字 select * from 被复制的表 where 1 = 2;
测试:mysql> create table userinfox2 select * from userinfo where 1 = 2;
多表查询:
格式一:select 字段名 from 表名,表名;
格式二:select 字段名 from 表名,表名 where 条件;
测试:mysql> select * from userinfox,hydra;
测试:mysql> select userinfo.name,userinfox.name from userinfo,userinfox where userinfo.uid = userinfox.uid;
连接查询:
左连接查询:left join ...on(以左边的表为主显示查询结果)
格式:select * from 左表 left join 右表 on 条件;
测试:mysql> select * from userinfo left join userinfox on userinfo.name=userinfox.name;
右链接查询:right join ...on(以右边的表为主显示查询结果)
格式:select * from 左表 right join 右表 on 条件;
测试:mysql> select * from userinfo right join userinfox on userinfo.name=userinfox.name;
修改表记录
批量修改:
格式:update 库名.表名 set 字段名=值,字段名=值;
测试:mysql> update userinfox set uid=0,gid=0;
修改符合条件记录字段的值:
格式:update 库名.表名 set 字段名=值,字段名=值 where 条件;
测试:mysql> update userinfox set homedir="/opt" where name="/bin/bash";
删除表记录
删除所有记录:
格式:delete from 表名;
测试:delete from hydra01;
删除符合条件的记录:
格式:delete from 表名 where 条件;
测试:mysql> delete from userinfo where id is not null;
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