mysql数据操作

千家信息网最后更新 2024年09月21日mysql数据操作

一、插入数据INSERT

1.插入完整数据（顺序插入）
语法一：
INSERT INTO 表名(字段1, 字段2, 字段3…字段n) VALUES(值1, 值2, 值3…值n);

语法二：
INSERT INTO 表名 VALUES(值1, 值2, 值3…值n);

2.指定字段插入数据
语法：
INSERT INTO 表名(字段1, 字段2, 字段3…) VALUES(值1, 值2, 值3…);

3.插入多条记录
语法：
INSERT INTO 表名 VALUES
(值1, 值2, 值3…值n),
(值1, 值2, 值3…值n),
(值1, 值2, 值3…值n);

4.插入查询结果
语法：
INSERT INTO 表名(字段1, 字段2, 字段3…字段n)
SELECT(字段1, 字段2, 字段3…字段n) FROM 表2
WHERE …;

二、更新数据UPDATE
语法：
UPDATE 表名 SET
字段1=值1,
字段2=值2,
WHERE CONDITION;

示例：
UPDATE mysql.user SET password=password('123') where user='root' and host='localhost';

三、删除数据DELETE
语法：
DELETE FROM 表名
WHERE CONITION;

示例：
DELETE FROM mysql.user
WHERE password='';
四、权限管理
#创建用户
create user 'egon'@'1.1.1.1' identified by '123';
create user 'egon'@'192.168.1.%' identified by '123';
create user 'egon'@'%' identified by '123';


#授权：对文件夹，对文件，对文件某一字段的权限
查看帮助：help grant
常用权限有：select,update,alter,delete
all可以代表除了grant之外的所有权限

#针对所有库的授权:*.*grant select on *.* to 'li'@'localhost' identified by '123'; #只在user表中可以查到li用户的select权限被设置为Y#针对某一数据库：db1.*grant select on db1.* to 'wang'@'%' identified by '123'; #只在db表中可以查到wang用户的select权限被设置为Y#针对某一个表：db1.t1grant select on db1.t1 to 'tom'@'%' identified by '123';  #只在tables_priv表中可以查到tom用户的select权限#针对某一个字段：mysql> select * from t3;+------+-------+------+| id   | name  | age  |+------+-------+------+|    1 | egon1 |   18 ||    2 | egon2 |   19 ||    3 | egon3 |   29 |+------+-------+------+grant select (id,name),update (age) on db1.t3 to 'egon4'@'localhost' identified by '123';#可以在tables_priv和columns_priv中看到相应的权限mysql> select * from tables_priv where user='egon4'\Gmysql> select * from columns_priv where user='egon4'\G#删除权限revoke select on db1.* to 'alex'@'%';

五、mysql单表查询
1、单表查询的语法
SELECT 字段1,字段2... FROM 表名
WHERE 条件
GROUP BY field
HAVING 筛选
ORDER BY field
LIMIT 限制条数
2、关键字的执行优先级
from #找到表
where #拿着where指定的约束条件，去文件/表中取出一条条记录
group by #将取出的一条条记录进行分组group by，如果没有group by，则整体作为一组
having #将分组的结果进行having过滤
select #执行select
distinct #去重
order by #将结果按条件排序
limit #限制结果的显示条数

3、简单查询

#创建表create database company;use company;create table employee(id int not null unique auto_increment,name varchar(20) not null,sex enum('male','female') not null default 'male',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,depart_id int);#插入记录三个部门：教学，销售，运营insert into employee(name,sex,age,hire_date,post,salary,office,depart_id) values('wang','male',18,'20170301','teacher',7300.33,401,1),('li','male',78,'20150302','teacher',1000000.31,401,1),('jim','male',81,'20130305','teacher',8300,401,1),('zhao','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),('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),('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);+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+| id | name       | sex    | age | hire_date  | post      | post_comment | salary     | office | depart_id |+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+|  1 | wang       | male   |  18 | 2017-03-01 | teacher   | NULL         |    7300.33 |    401 |         1 ||  2 | li         | male   |  78 | 2015-03-02 | teacher   | NULL         | 1000000.31 |    401 |         1 ||  3 | jim        | male   |  81 | 2013-03-05 | teacher   | NULL         |    8300.00 |    401 |         1 ||  4 | zhao       | 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 ||  9 | 歪歪       | female |  48 | 2015-03-11 | sale      | NULL         |    3000.13 |    402 |         2 || 10 | 丫丫       | female |  38 | 2010-11-01 | sale      | NULL         |    2000.35 |    402 |         2 || 11 | 丁丁       | female |  18 | 2011-03-12 | sale      | NULL         |    1000.37 |    402 |         2 || 12 | 星星       | female |  18 | 2016-05-13 | sale      | NULL         |    3000.29 |    402 |         2 || 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 || 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 |+----+------------+--------+-----+------------+-----------+--------------+------------+--------+-----------+# 简单查询SELECT id, name, sex, age, hire_date, post, post_comment, salary, office, depart_id FROM employee;SELECT * FROM employee;SELECT name, salary FROM employee;# 避免重复DISTINCTSELECT DISTINCT post FROM employee;+-----------+| post      |+-----------+| teacher   || sale      || operation |+-----------+# 通过四则运算查询SELECT name, salary * 12 FROM employee;SELECT name, salary * 12 AS Annual_salary FROM employee;SELECT name, salary * 12 Annual_salary FROM employee;+------------+---------------+| name       | Annual_salary |+------------+---------------+| wang       |      87603.96 || li         |   12000003.72 || jim        |      99600.00 || zhao       |      42000.00 || liwenzhou  |      25200.00 || jingliyang |     108000.00 || jinxin     |     360000.00 || 成龙       |     120000.00 || 歪歪       |      36001.56 || 丫丫       |      24004.20 || 丁丁       |      12004.44 || 星星       |      36003.48 || 格格       |      48003.96 || 张野       |     120001.56 || 程咬金     |     240000.00 || 程咬银     |     228000.00 || 程咬铜     |     216000.00 || 程咬铁     |     204000.00 |+------------+---------------+# 定义显示格式CONCAT() 函数用于连接字符串SELECT CONCAT('姓名: ', name, '  年薪: ', salary * 12) AS Annual_salary FROM employee;CONCAT_WS() 第一个参数为分隔符SELECT CONCAT_WS(':', name, salary * 12) AS Annual_salary FROM employee;+----------------------+| Annual_salary        |+----------------------+| wang:87603.96        || li:12000003.72       || jim:99600.00         || zhao:42000.00        || liwenzhou:25200.00   || jingliyang:108000.00 || jinxin:360000.00     || 成龙:120000.00       || 歪歪:36001.56        || 丫丫:24004.20        || 丁丁:12004.44        || 星星:36003.48        || 格格:48003.96        || 张野:120001.56       || 程咬金:240000.00     || 程咬银:228000.00     || 程咬铜:216000.00     || 程咬铁:204000.00     |+----------------------+

练习：
（1）查出所有员工的名字，薪资,格式为
<名字:egon> <薪资:3000>
（2）查出所有的岗位（去掉重复）
（3）查出所有员工名字，以及他们的年薪,年薪的字段名为annual_year

select concat('<名字:',name,'>    ','<薪资:',salary,'>') from employee;select distinct depart_id from employee;select name,salary*12 annual_salary from employee;

4、WHERE约束

# 1:单条件查询SELECT name FROM employee WHERE post = 'sale';# 2:多条件查询SELECT name, salary FROM employee WHERE post = 'teacher' AND salary > 10000;# 3:关键字BETWEEN ANDSELECT name, salary FROM employee WHERE salary BETWEEN 10000 AND 20000;SELECT name, salary FROM employee WHERE salary NOT BETWEEN 10000 AND 20000;# 4:关键字IS NULL(判断某个字段是否为NULL不能用等号，需要用IS)SELECT name, post_comment FROM employee WHERE post_comment IS NULL;SELECT name, post_comment FROM employee WHERE post_comment IS NOT NULL;SELECT name, post_comment FROM employee WHERE post_comment = '';  #注意''是空字符串，不是nullps：    执行    update employee set post_comment = '' where id = 2;    再用上条查看，就会有结果了# 5:关键字IN集合查询SELECT name, salary FROM employee WHERE salary = 3000 OR salary = 3500 OR salary = 4000 OR salary = 9000;SELECT name, salary FROM employee WHERE salary IN(3000, 3500, 4000, 9000);SELECT name, salary FROM employee WHERE salary NOT IN(3000, 3500, 4000, 9000);# 6:关键字LIKE模糊查询通配符' % 'SELECT * FROM employee WHERE name LIKE 'eg%';通配符'_'SELECT * FROM employee WHERE name LIKE 'al__';

练习：
（1）查看岗位是teacher的员工姓名、年龄
（2）查看岗位是teacher且年龄大于30岁的员工姓名、年龄
（3）查看岗位是teacher且薪资在9000-1000范围内的员工姓名、年龄、薪资
（4）查看岗位描述不为NULL的员工信息
（5）查看岗位是teacher且薪资是10000或9000或30000的员工姓名、年龄、薪资
（6）查看岗位是teacher且薪资不是10000或9000或30000的员工姓名、年龄、薪资
（7）查看岗位是teacher且名字是jin开头的员工姓名、年薪

select name,age from employee where post = 'teacher';select name,age from employee where post='teacher' and age > 30;select name,age,salary from employee where post='teacher' and salary between 9000 and 10000;select * from employee where post_comment is not null;select name,age,salary from employee where post='teacher' and salary in (10000,9000,30000);select name,age,salary from employee where post='teacher' and salary not in (10000,9000,30000);select name,salary*12 from employee where post='teacher' and name like 'jin%';mysql> select name,salary*12 as year_salary from employee where post='teacher' and name like 'jin%';

5、分组查询:GROUP BY

（1）GROUP BY
单独使用GROUP BY关键字分组
SELECT post FROM employee GROUP BY post;
注意：我们按照post字段分组，那么select查询的字段只能是post，想要获取组内的其他相关信息，需要借助函数

GROUP BY关键字和GROUP_CONCAT()函数一起使用
SELECT post,GROUP_CONCAT(name) FROM employee GROUP BY post; #按照岗位分组，并查看组内成员名
SELECT post,GROUP_CONCAT(name) as emp_members FROM employee GROUP BY post;

GROUP BY与聚合函数一起使用
select post,count(id) as count from employee group by post; #按照岗位分组，并查看每个组有多少人

如果我们用unique的字段作为分组的依据，则每一条记录自成一组，这种分组没有意义
多条记录之间的某个字段值相同，该字段通常用来作为分组的依据

（2）聚合函数
#强调：聚合函数聚合的是组的内容，若是没有分组，则默认一组

示例：
SELECT COUNT(*) FROM employee;
SELECT COUNT(*) FROM employee WHERE depart_id=1;
SELECT MAX(salary) FROM employee;
SELECT MIN(salary) FROM employee;
SELECT AVG(salary) FROM employee;
SELECT SUM(salary) FROM employee;
SELECT SUM(salary) FROM employee WHERE depart_id=3;

练习：
（1）查询岗位名以及岗位包含的所有员工名字
（2）查询岗位名以及各岗位内包含的员工个数
（3）查询公司内男员工和女员工的个数
（4）查询岗位名以及各岗位的平均薪资
（5）查询岗位名以及各岗位的最高薪资
（6）查询岗位名以及各岗位的最低薪资
（7）查询男员工与男员工的平均薪资，女员工与女员工的平均薪资

mysql> select post,group_concat(name) from employee group by post;mysql> select post,count(id) from employee group by post;mysql> select sex,count(id) from employee group by sex;mysql> select post,avg(salary) from employee group by post;mysql> select post,max(salary) from employee group by post;mysql> select post,min(salary) from employee group by post;mysql> select sex,avg(salary) from employee group by sex;

6、HAVING过滤

HAVING与WHERE不一样的地方在于!!!!!!
#！！！执行优先级从高到低：where > group by > having
#1. Where 发生在分组group by之前，因而Where中可以有任意字段，但是绝对不能使用聚合函数。
#2. Having发生在分组group by之后，因而Having中可以使用分组的字段，无法直接取到其他字段,可以使用聚合函数

练习：
1. 查询各岗位内包含的员工个数小于2的岗位名、岗位内包含员工名字、个数
2. 查询各岗位平均薪资大于10000的岗位名、平均工资
3. 查询各岗位平均薪资大于10000且小于20000的岗位名、平均工资

mysql> select post,group_concat(name),count(id) from employee group by post having count(id) < 2;mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000;mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 and avg(salary) <20000;

7、查询排序:ORDER BY

按单列排序
SELECT * FROM employee ORDER BY salary;
SELECT * FROM employee ORDER BY salary ASC;
SELECT * FROM employee ORDER BY salary DESC;

按多列排序:先按照age排序，如果年纪相同，则按照薪资排序
SELECT * from employee ORDER BY age,salary DESC;

练习：
1. 查询所有员工信息，先按照age升序排序，如果age相同则按照hire_date降序排序
2. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资升序排列
3. 查询各岗位平均薪资大于10000的岗位名、平均工资,结果按平均薪资降序排列

mysql> select * from employee ORDER BY age asc,hire_date desc;mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) asc;mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) desc;

8、限制查询的记录数:LIMIT

SELECT * FROM employee ORDER BY salary DESC LIMIT 3;  # 默认初始位置为0SELECT * FROM employee ORDER BY salary DESC LIMIT 0, 5;  # 从第0开始，即先查询出第一条，然后包含这一条在内往后查5条SELECT * FROM employee ORDER BY salary DESC LIMIT 5, 5;  # 从第5开始，即先查询出第6条，然后包含这一条在内往后查5条

练习：分页显示，每页5条

mysql> select * from  employee limit 0,5;              #显示第1到5条记录mysql> select * from  employee limit 5,5;              #显示第5到10条记录mysql> select * from  employee limit 10,5;             #显示第10到15条记录

9、使用正则表达式查询

SELECT * FROM employee WHERE name REGEXP '^ale';SELECT * FROM employee WHERE name REGEXP 'on$';SELECT * FROM employee WHERE name REGEXP 'm{2}';

小结：对字符串匹配的方式
WHERE name = 'li';
WHERE name LIKE 'yua%';
WHERE name REGEXP 'on$';

练习：
查看所有员工中名字是jin开头，n或者g结果的员工信息

select * from employee where name regexp '^jin.*[gn]$';

六、mysql多表查询
1、建表

create table department(id int,name varchar(20));create table employee(id int primary key auto_increment,name varchar(20),sex enum('male','female') not null default 'male',age int,dep_id int);#插入数据insert into department values(200,'技术'),(201,'人力资源'),(202,'销售'),(203,'运营');insert into employee(name,sex,age,dep_id) values('egon','male',18,200),('alex','female',48,201),('wupeiqi','male',38,201),('yuanhao','female',28,202),('liwenzhou','male',18,200),('jingliyang','female',18,204);

2、多表连接查询
（1）交叉连接：不适用任何匹配条件。生成笛卡尔积

mysql> select * from department;+------+--------------+| id   | name         |+------+--------------+|  200 | 技术         ||  201 | 人力资源     ||  202 | 销售         ||  203 | 运营         |+------+--------------+mysql> select * from employee;+----+------------+--------+------+--------+| id | name       | sex    | age  | dep_id |+----+------------+--------+------+--------+|  1 | egon       | male   |   18 |    200 ||  2 | alex       | female |   48 |    201 ||  3 | wupeiqi    | male   |   38 |    201 ||  4 | yuanhao    | female |   28 |    202 ||  5 | liwenzhou  | male   |   18 |    200 ||  6 | jingliyang | female |   18 |    204 |+----+------------+--------+------+--------+mysql> select * from employee,department;

（2）内连接：只连接匹配的行

#找两张表共有的部分，相当于利用条件从笛卡尔积结果中筛选出了正确的结果
#department没有204这个部门，因而employee表中关于204这条员工信息没有匹配出来

mysql> select employee.id,employee.name,employee.age,employee.sex,department.name from employee inner join department on employee.dep_id=department.id;+----+-----------+------+--------+--------------+| id | name      | age  | sex    | name         |+----+-----------+------+--------+--------------+|  1 | egon      |   18 | male   | 技术         ||  2 | alex      |   48 | female | 人力资源     ||  3 | wupeiqi   |   38 | male   | 人力资源     ||  4 | yuanhao   |   28 | female | 销售         ||  5 | liwenzhou |   18 | male   | 技术         |+----+-----------+------+--------+--------------+mysql> select employee.id,employee.name,employee.age,employee.sex,department.name from employee,department where employee.dep_id=department.id;

（3）外链接之左连接：优先显示左表全部记录

#以左表为准，即找出所有员工信息，当然包括没有部门的员工
#本质就是：在内连接的基础上增加左边有右边没有的结果

mysql> select employee.id,employee.name,department.name as depart_name from employee left join department on employee.dep_id=department.id;+----+------------+--------------+| id | name       | depart_name  |+----+------------+--------------+|  1 | egon       | 技术         ||  5 | liwenzhou  | 技术         ||  2 | alex       | 人力资源     ||  3 | wupeiqi    | 人力资源     ||  4 | yuanhao    | 销售         ||  6 | jingliyang | NULL         |+----+------------+--------------+

（4）外链接之右连接：优先显示右表全部记录

#以右表为准，即找出所有部门信息，包括没有员工的部门
#本质就是：在内连接的基础上增加右边有左边没有的结果

mysql> select employee.id,employee.name,department.name as depart_name from employee right join department on employee.dep_id=department.id;+------+-----------+--------------+| id   | name      | depart_name  |+------+-----------+--------------+|    1 | egon      | 技术         ||    2 | alex      | 人力资源     ||    3 | wupeiqi   | 人力资源     ||    4 | yuanhao   | 销售         ||    5 | liwenzhou | 技术         || NULL | NULL      | 运营         |+------+-----------+--------------+

（5）全外连接：显示左右两个表全部记录

全外连接：在内连接的基础上增加左边有右边没有的和右边有左边没有的结果
#注意：mysql不支持全外连接 full JOIN

#强调：mysql可以使用此种方式间接实现全外连接

select * from employee left join department on employee.dep_id = department.idunionselect * from employee right join department on employee.dep_id = department.id;+------+------------+--------+------+--------+------+--------------+| id   | name       | sex    | age  | dep_id | id   | name         |+------+------------+--------+------+--------+------+--------------+|    1 | egon       | male   |   18 |    200 |  200 | 技术         ||    5 | liwenzhou  | male   |   18 |    200 |  200 | 技术         ||    2 | alex       | female |   48 |    201 |  201 | 人力资源     ||    3 | wupeiqi    | male   |   38 |    201 |  201 | 人力资源     ||    4 | yuanhao    | female |   28 |    202 |  202 | 销售         ||    6 | jingliyang | female |   18 |    204 | NULL | NULL         || NULL | NULL       | NULL   | NULL |   NULL |  203 | 运营         |+------+------------+--------+------+--------+------+--------------+#注意 union与union all的区别：union会去掉相同的纪录

3、符合条件连接查询

#示例1：以内连接的方式查询employee和department表，并且employee表中的age字段值必须大于25,即找出年龄大于25岁的员工以及员工所在的部门select employee.name,department.name from employee inner join department on employee.dep_id = department.id where age > 25;+---------+--------------+| name    | name         |+---------+--------------+| alex    | 人力资源     || wupeiqi | 人力资源     || yuanhao | 销售         |+---------+--------------+#示例2：以内连接的方式查询employee和department表，并且以age字段的升序方式显示select employee.id,employee.name,employee.age,department.name from employee,department where employee.dep_id = department.id and age > 25 order by age asc;+----+---------+------+--------------+| id | name    | age  | name         |+----+---------+------+--------------+|  4 | yuanhao |   28 | 销售         ||  3 | wupeiqi |   38 | 人力资源     ||  2 | alex    |   48 | 人力资源     |+----+---------+------+--------------+

4、子查询
#1：子查询是将一个查询语句嵌套在另一个查询语句中。
#2：内层查询语句的查询结果，可以为外层查询语句提供查询条件。
#3：子查询中可以包含：IN、NOT IN、ANY、ALL、EXISTS 和 NOT EXISTS等关键字
#4：还可以包含比较运算符：= 、 !=、> 、<等

（1）带IN关键字的子查询

#查询平均年龄在25岁以上的部门名select id,name from department where id in (select dep_id from employee group by dep_id having avg(age) > 25);#查看技术部员工姓名select name from employee where dep_id in (select id from department where name='技术');#查看不足1人的部门名(子查询得到的是有人的部门id)select name from department where id not in (select distinct dep_id from employee);

（2）带比较运算符的子查询
#比较运算符：=、!=、>、>=、<、<=、<>

#查询大于所有人平均年龄的员工名与年龄mysql> select name,age from emp where age > (select avg(age) from emp);#查询大于部门内平均年龄的员工名、年龄select t1.name,t1.age from emp t1inner join(select dep_id,avg(age) avg_age from emp group by dep_id) t2 on t1.dep_id = t2.dep_id where t1.age > t2.avg_age;

（3）带EXISTS关键字的子查询
EXISTS关字键字表示存在。在使用EXISTS关键字时，内层查询语句不返回查询的记录。
而是返回一个真假值。True或False
当返回True时，外层查询语句将进行查询；当返回值为False时，外层查询语句不进行查询

#department表中存在dept_id=203，Turemysql> select * from employee where exists (select id from department where id=200);#department表中存在dept_id=205，Falsemysql> select * from employee where exists (select id from department where id=204);