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数据库mysql+401.1_MySQL 数据库

作者：Cpp五条 | 2024-02-16 02:59:07

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连接mysql 401

1.插入数据：

create table 加新表名 (字段数据类型 [约束条件] ...) select 加字段...from 加旧表名；

create table 加新表名 (字段数据类型 [约束条件] ...)select 加字段 as 加别名 from 旧表名 [where 条件]；

as 起一个别名，起别名是，默认有as 所以可以不用加as 就可以起别名。

mysql> create table t1(id int primary key auto_increment,

-> name char(10) not null,

-> age int not null);

Query OK, 0 rows affected (0.38 sec)

mysql> insert into t1(name,age)values('liny',18),('linyuz',17),('aaaa',21);

Query OK, 3 rows affected (0.06 sec)

Records: 3 Duplicates: 0 Warnings: 0

mysql> desc t1;

+-------+----------+------+-----+---------+----------------+

+-------+----------+------+-----+---------+----------------+

| id | int(11) | NO | PRI | NULL | auto_increment |

| age | int(11) | NO | | NULL | |

+-------+----------+------+-----+---------+----------------+

3 rows in set (0.00 sec)

mysql> select * from t1;

+----+--------+-----+

| id | name | age |

+----+--------+-----+

| 1 | liny | 18 |

| 2 | linyuz | 17 |

| 3 | aaaa | 21 |

+----+--------+-----+

3 rows in set (0.00 sec)

mysql> create table t2(name char(10) not null,

-> age int not null) select name,age from t1;

Query OK, 3 rows affected (0.32 sec)

Records: 3 Duplicates: 0 Warnings: 0

mysql> desc t2;

+-------+----------+------+-----+---------+-------+

+-------+----------+------+-----+---------+-------+

| age | int(11) | NO | | NULL | |

+-------+----------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql> select * from t2;

+--------+-----+

| name | age |

+--------+-----+

| liny | 18 |

| linyuz | 17 |

| aaaa | 21 |

+--------+-----+

3 rows in set (0.00 sec)

mysql> create table t3(x char(10) not null,

-> a int not null) select name as x,age a from t1;

Query OK, 3 rows affected (0.31 sec)

Records: 3 Duplicates: 0 Warnings: 0

mysql> desc t3;

+-------+----------+------+-----+---------+-------+

+-------+----------+------+-----+---------+-------+

| x | char(10) | NO | | NULL | |

| a | int(11) | NO | | NULL | |

+-------+----------+------+-----+---------+-------+

2 rows in set (0.00 sec)

mysql> select * from t3;

+--------+----+

| x | a |

+--------+----+

| liny | 18 |

| linyuz | 17 |

| aaaa | 21 |

+--------+----+

3 rows in set (0.00 sec)

2.修改数据：

update 加表名 set 字段=记录 where 加条件；

mysql> create table t1(id int primary key auto_increment,

-> name char(10) not null,

-> age int not null);

Query OK, 0 rows affected (0.38 sec)

mysql> insert into t1(name,age)values('liny',18),('linyuz',17),('aaaa',21);

Query OK, 3 rows affected (0.06 sec)

Records: 3 Duplicates: 0 Warnings: 0

mysql> desc t1;

+-------+----------+------+-----+---------+----------------+

+-------+----------+------+-----+---------+----------------+

| id | int(11) | NO | PRI | NULL | auto_increment |

| age | int(11) | NO | | NULL | |

+-------+----------+------+-----+---------+----------------+

3 rows in set (0.00 sec)

mysql> select * from t1;

+----+--------+-----+

| id | name | age |

+----+--------+-----+

| 1 | liny | 18 |

| 2 | linyuz | 17 |

| 3 | aaaa | 21 |

+----+--------+-----+

3 rows in set (0.00 sec)

mysql> update t1 set name='aaa' where id=3 and age=21;

Query OK, 1 row affected (0.08 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> select * from t1;

+----+--------+-----+

| id | name | age |

+----+--------+-----+

| 1 | liny | 18 |

| 2 | linyuz | 17 |

| 3 | aaa | 21 |

+----+--------+-----+

3 rows in set (0.00 sec)

3 杂碎的内容：

concat：字符串的拼接，可以拼成任意的格式

concat_ws：第一个参数指定的是分割符，后面加上自己要看的字段

\G：将乱了的记录重新按行显示。

二常用的select查看

select 的基本格式：

select distinot：去重字段名。。。 from 表名

where 约束条件：取出来的记录默认为是一个组，在这里就可以使用聚合函数，约束条件就是默认某些字段的约束。

group by 字段名：后面加上某个字段，就会按照那个字段分组，分组过后可以直接查看分组的字段，要想查看其他的字段，必须要借助聚合函数，分组是为了一类一类的处理数据。而分组的字段是依据字段的约束条件不唯一。

having 过滤语句：只能跟在分组的后面，处理一些分组过后的约束条件。

order by 字段排序：排序。后面加上需要按照排序的字段，后面可以同时加上多个排序条件，如果前面的排序有重复的，才会执行后面的，如果没有重复的，后面的就不会执行。他是在取出了相应字段的记录后才开始执行的。

limit 限制条件：规定查看的范围，在最后才开始运行。

准备表：

mysql> use day44;

Database changed

mysql> create table employee(

-> id int not null unique auto_increment,

-> name varchar(20) not null,

-> sex enum('male','female') not null default 'male', #大部分是男的

-> age int(3) unsigned not null default 28,

-> hire_date date not null,

-> post varchar(50),

-> post_comment varchar(100),

-> salary double(15,2),

-> office int, #一个部门一个屋子

-> depart_id int

-> );

Query OK, 0 rows affected (0.28 sec)

mysql>

mysql> #查看表结构

mysql> desc employee;

+--------------+-----------------------+------+-----+---------+----------------+

+--------------+-----------------------+------+-----+---------+----------------+

| id | int(11) | NO | PRI | NULL | auto_increment |

| sex | enum('male','female') | NO | | male | |

| age | int(3) unsigned | NO | | 28 | |

| office | int(11) | YES | | NULL | |

| depart_id | int(11) | YES | | NULL | |

+--------------+-----------------------+------+-----+---------+----------------+

10 rows in set (0.01 sec)

mysql>

mysql> #插入记录

mysql> #三个部门：教学，销售，运营

mysql> insert into employee(name,sex,age,hire_date,post,salary,office,depart_id) values

-> ('egon','male',18,'20170301','老男孩驻沙河办事处外交大使',7300.33,401,1), #以下是教学部

-> ('alex','male',78,'20150302','teacher',1000000.31,401,1),

-> ('wupeiqi','male',81,'20130305','teacher',8300,401,1),

-> ('yuanhao','male',73,'20140701','teacher',3500,401,1),

-> ('liwenzhou','male',28,'20121101','teacher',2100,401,1),

-> ('jingliyang','female',18,'20110211','teacher',9000,401,1),

-> ('jinxin','male',18,'19000301','teacher',30000,401,1),

-> ('成龙','male',48,'20101111','teacher',10000,401,1),

-> ('歪歪','female',48,'20150311','sale',3000.13,402,2),#以下是销售部门

-> ('丫丫','female',38,'20101101','sale',2000.35,402,2),

-> ('丁丁','female',18,'20110312','sale',1000.37,402,2),

-> ('星星','female',18,'20160513','sale',3000.29,402,2),

-> ('格格','female',28,'20170127','sale',4000.33,402,2),

-> ('张野','male',28,'20160311','operation',10000.13,403,3), #以下是运营部门

-> ('程咬金','male',18,'19970312','operation',20000,403,3),

-> ('程咬银','female',18,'20130311','operation',19000,403,3),

-> ('程咬铜','male',18,'20150411','operation',18000,403,3),

-> ('程咬铁','female',18,'20140512','operation',17000,403,3)

-> ;

Query OK, 18 rows affected (0.09 sec)

Records: 18 Duplicates: 0 Warnings: 0

集合函数：min：最小值 max：最大值 avg：计算平均值 sum：计算总和 count：计算个数

where 条件约束：后面可以加上比较符号(> <= >=) 逻辑运算符(and or not) 注：<>与!=是对等的，<>不常用！

in：什么或什么或什么 between：在什么和什么之间 like：像什么后面出入两个符号 % ：任意多个字符 _ ：表示任意一个字符 is：什么是什么

mysql> select * from employee where age>50;

+----+---------+------+-----+------------+---------+--------------+------------+--------+-----------+

+----+---------+------+-----+------------+---------+--------------+------------+--------+-----------+

| 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 |

| 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 |

| 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 |

+----+---------+------+-----+------------+---------+--------------+------------+--------+-----------+

3 rows in set (0.00 sec)

mysql> select * from employee where sex='male' and salary>30000;

+----+------+------+-----+------------+---------+--------------+------------+--------+-----------+

+----+------+------+-----+------------+---------+--------------+------------+--------+-----------+

| 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 |

+----+------+------+-----+------------+---------+--------------+------------+--------+-----------+

1 row in set (0.00 sec)

mysql> select * from employee where post='teacher' or salary>30000;

+----+------------+--------+-----+------------+---------+--------------+------------+--------+-----------+

+----+------------+--------+-----+------------+---------+--------------+------------+--------+-----------+

| 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 |

| 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 |

| 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 |

| 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 |

| 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 |

| 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 |

| 8 | 成龙 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 |

+----+------------+--------+-----+------------+---------+--------------+------------+--------+-----------+

7 rows in set (0.00 sec)

mysql> select * from employee where age between 20 and 30;

+----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

+----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

| 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 |

| 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 |

| 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 |

+----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

3 rows in set (0.01 sec)

mysql> select * from employee where id in(3,6,16) or name like '程%';

+----+------------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

+----+------------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

| 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 |

| 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 |

| 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 |

| 16 | 程咬银 | female | 18 | 2013-03-11 | operation | NULL | 19000.00 | 403 | 3 |

| 17 | 程咬铜 | male | 18 | 2015-04-11 | operation | NULL | 18000.00 | 403 | 3 |

| 18 | 程咬铁 | female | 18 | 2014-05-12 | operation | NULL | 17000.00 | 403 | 3 |

+----+------------+--------+-----+------------+-----------+--------------+----------+--------+-----------+

6 rows in set (0.44 sec)

注：如发现格式不对，可以在mysql中试试。

group by 分组：后面加上一个字段名

mysql> select post,count(id),group_concat(name) from employee group by post;

+----------------------------+-----------+-------------------------------------------------------+

| post | count(id) | group_concat(name) |

+----------------------------+-----------+-------------------------------------------------------+

| operation | 5 | 张野,程咬金,程咬银,程咬铜,程咬铁 |

| sale | 5 | 歪歪,丫丫,丁丁,星星,格格 |

| teacher | 7 | alex,wupeiqi,yuanhao,liwenzhou,jingliyang,jinxin,成龙 |

| 老男孩驻沙河办事处外交大使 | 1 | egon |

+----------------------------+-----------+-------------------------------------------------------+

4 rows in set (0.00 sec)

mysql> select post,min(salary) from employee group by post;

+----------------------------+-------------+

| post | min(salary) |

+----------------------------+-------------+

| operation | 10000.13 |

| sale | 1000.37 |

| teacher | 2100.00 |

| 老男孩驻沙河办事处外交大使 | 7300.33 |

+----------------------------+-------------+

4 rows in set (0.00 sec)

mysql> select post,max(salary) from employee group by post;

+----------------------------+-------------+

| post | max(salary) |

+----------------------------+-------------+

| operation | 20000.00 |

| sale | 4000.33 |

| teacher | 1000000.31 |

| 老男孩驻沙河办事处外交大使 | 7300.33 |

+----------------------------+-------------+

4 rows in set (0.00 sec)

mysql> select post,sum(salary) from employee group by post;

+----------------------------+-------------+

| post | sum(salary) |

+----------------------------+-------------+

| operation | 84000.13 |

| sale | 13001.47 |

| teacher | 1062900.31 |

| 老男孩驻沙河办事处外交大使 | 7300.33 |

+----------------------------+-------------+

4 rows in set (0.00 sec)

mysql> select post,avg(salary) from employee group by post;

+----------------------------+---------------+

| post | avg(salary) |

+----------------------------+---------------+

| operation | 16800.026000 |

| sale | 2600.294000 |

| teacher | 151842.901429 |

| 老男孩驻沙河办事处外交大使 | 7300.330000 |

+----------------------------+---------------+

4 rows in set (0.00 sec)

having 过滤条件：后面加的内容和where一样，不过需要借助于聚合函数过滤记录

mysql> select post from employee group by post having count(id)>5;

+---------+

| post |

+---------+

| teacher |

+---------+

1 row in set (0.00 sec)

mysql> select post from employee group by post having count(id)>5 or avg(salary) >10000;

+-----------+

| post |

+-----------+

| operation |

| teacher |

+-----------+

2 rows in set (0.00 sec)

order by ：后面跟上：asc：升序，从小到大排序； desc：降序，从大到小排序。order by：默认是从小到达排序的。

mysql> select * from employee order by age asc,id desc;

+----+------------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+

+----+------------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+

| 18 | 程咬铁 | female | 18 | 2014-05-12 | operation | NULL | 17000.00 | 403 | 3 |

| 17 | 程咬铜 | male | 18 | 2015-04-11 | operation | NULL | 18000.00 | 403 | 3 |

| 16 | 程咬银 | female | 18 | 2013-03-11 | operation | NULL | 19000.00 | 403 | 3 |

| 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 |

| 12 | 星星 | female | 18 | 2016-05-13 | sale | NULL | 3000.29 | 402 | 2 |

| 11 | 丁丁 | female | 18 | 2011-03-12 | sale | NULL | 1000.37 | 402 | 2 |

| 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 |

| 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 |

| 1 | egon | male | 18 | 2017-03-01 | 老男孩驻沙河办事处外交大使 | NULL | 7300.33 | 401 | 1 |

| 14 | 张野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 |

| 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 |

| 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 |

| 10 | 丫丫 | female | 38 | 2010-11-01 | sale | NULL | 2000.35 | 402 | 2 |

| 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 |

| 8 | 成龙 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 |

| 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 |

| 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 |

| 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 |

+----+------------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+

18 rows in set (0.00 sec)

limit 限制条件：后面输入整数类型，只传一个值是查看记录的条数，默认从第1条记录开始查看，如果出入两个数，第一个数是初始值，就是从那一条的下一条开始查看，第二个数就是查看记录的条数。

mysql> select * from employee where id limit 6,10;

+----+--------+--------+-----+------------+-----------+--------------+----------+--------+-----------+