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:*.*grantselecton*.*to'li'@'localhost'identifiedby'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.*grantselectondb1.*to'wang'@'%'identifiedby'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.t1grantselectondb1.t1to'tom'@'%'identifiedby'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*fromt3;+------+-------+------+|id|name|age|+------+-------+------+|1|egon1|18||2|egon2|19||3|egon3|29|+------+-------+------+grantselect(id,name),update(age)ondb1.t3to'egon4'@'localhost'identifiedby'123';#可以在tables_priv和columns_priv中看到相应的权限mysql>select*fromtables_privwhereuser='egon4'\Gmysql>select*fromcolumns_privwhereuser='egon4'\G#删除权限revokeselectondb1.*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createdatabasecompany;usecompany;createtableemployee(idintnotnulluniqueauto_increment,namevarchar(20)notnull,sexenum('male','female')notnulldefault'male',ageint(3)unsignednotnulldefault28,hire_datedatenotnull,postvarchar(50),post_commentvarchar(100),salarydouble(15,2),officeint,depart_idint);#插入记录三个部门：教学，销售，运营insertintoemployee(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SELECTid,name,sex,age,hire_date,post,post_comment,salary,office,depart_idFROMemployee;SELECT*FROMemployee;SELECTname,salaryFROMemployee;#避免重复DISTINCTSELECTDISTINCTpostFROMemployee;+-----------+|post|+-----------+|teacher||sale||operation|+-----------+#通过四则运算查询SELECTname,salary*12FROMemployee;SELECTname,salary*12ASAnnual_salaryFROMemployee;SELECTname,salary*12Annual_salaryFROMemployee;+------------+---------------+|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SELECTCONCAT('姓名:',name,'年薪:',salary*12)ASAnnual_salaryFROMemployee;CONCAT_WS()第一个参数为分隔符SELECTCONCAT_WS(':',name,salary*12)ASAnnual_salaryFROMemployee;+----------------------+|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

selectconcat('<名字:',name,'>','<薪资:',salary,'>')fromemployee;selectdistinctdepart_idfromemployee;selectname,salary*12annual_salaryfromemployee;

4、WHERE约束

#1:单条件查询SELECTnameFROMemployeeWHEREpost='sale';#2:多条件查询SELECTname,salaryFROMemployeeWHEREpost='teacher'ANDsalary>10000;#3:关键字BETWEENANDSELECTname,salaryFROMemployeeWHEREsalaryBETWEEN10000AND20000;SELECTname,salaryFROMemployeeWHEREsalaryNOTBETWEEN10000AND20000;#4:关键字ISNULL(判断某个字段是否为NULL不能用等号，需要用IS)SELECTname,post_commentFROMemployeeWHEREpost_commentISNULL;SELECTname,post_commentFROMemployeeWHEREpost_commentISNOTNULL;SELECTname,post_commentFROMemployeeWHEREpost_comment='';#注意''是空字符串，不是nullps：执行updateemployeesetpost_comment=''whereid=2;再用上条查看，就会有结果了#5:关键字IN集合查询SELECTname,salaryFROMemployeeWHEREsalary=3000ORsalary=3500ORsalary=4000ORsalary=9000;SELECTname,salaryFROMemployeeWHEREsalaryIN(3000,3500,4000,9000);SELECTname,salaryFROMemployeeWHEREsalaryNOTIN(3000,3500,4000,9000);#6:关键字LIKE模糊查询通配符’%’SELECT*FROMemployeeWHEREnameLIKE'eg%';通配符’_’SELECT*FROMemployeeWHEREnameLIKE'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

selectname,agefromemployeewherepost='teacher';selectname,agefromemployeewherepost='teacher'andage>30;selectname,age,salaryfromemployeewherepost='teacher'andsalarybetween9000and10000;select*fromemployeewherepost_commentisnotnull;selectname,age,salaryfromemployeewherepost='teacher'andsalaryin(10000,9000,30000);selectname,age,salaryfromemployeewherepost='teacher'andsalarynotin(10000,9000,30000);selectname,salary*12fromemployeewherepost='teacher'andnamelike'jin%';mysql>selectname,salary*12asyear_salaryfromemployeewherepost='teacher'andnamelike'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>selectpost,group_concat(name)fromemployeegroupbypost;mysql>selectpost,count(id)fromemployeegroupbypost;mysql>selectsex,count(id)fromemployeegroupbysex;mysql>selectpost,avg(salary)fromemployeegroupbypost;mysql>selectpost,max(salary)fromemployeegroupbypost;mysql>selectpost,min(salary)fromemployeegroupbypost;mysql>selectsex,avg(salary)fromemployeegroupbysex;

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>selectpost,group_concat(name),count(id)fromemployeegroupbyposthavingcount(id)<2;mysql>selectpost,avg(salary)fromemployeegroupbyposthavingavg(salary)>10000;mysql>selectpost,avg(salary)fromemployeegroupbyposthavingavg(salary)>10000andavg(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*fromemployeeORDERBYageasc,hire_datedesc;mysql>selectpost,avg(salary)fromemployeegroupbyposthavingavg(salary)>10000orderbyavg(salary)asc;mysql>selectpost,avg(salary)fromemployeegroupbyposthavingavg(salary)>10000orderbyavg(salary)desc;

8、限制查询的记录数:LIMIT

SELECT*FROMemployeeORDERBYsalaryDESCLIMIT3;#默认初始位置为0SELECT*FROMemployeeORDERBYsalaryDESCLIMIT0,5;#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*FROMemployeeORDERBYsalaryDESCLIMIT5,5;#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*fromemployeelimit0,5;#显示第1到5条记录mysql>select*fromemployeelimit5,5;#显示第5到10条记录mysql>select*fromemployeelimit10,5;#显示第10到15条记录

9、使用正则表达式查询

SELECT*FROMemployeeWHEREnameREGEXP'^ale';SELECT*FROMemployeeWHEREnameREGEXP'on$';SELECT*FROMemployeeWHEREnameREGEXP'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

createtabledepartment(idint,namevarchar(20));createtableemployee(idintprimarykeyauto_increment,namevarchar(20),sexenum('male','female')notnulldefault'male',ageint,dep_idint);#插入数据insertintodepartmentvalues(200,'技术'),(201,'人力资源'),(202,'销售'),(203,'运营');insertintoemployee(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*fromdepartment;+------+--------------+|id|name|+------+--------------+|200|技术||201|人力资源||202|销售||203|运营|+------+--------------+mysql>select*fromemployee;+----+------------+--------+------+--------+|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*fromemployee,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>selectemployee.id,employee.name,employee.age,employee.sex,department.namefromemployeeinnerjoindepartmentonemployee.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>selectemployee.id,employee.name,employee.age,employee.sex,department.namefromemployee,departmentwhereemployee.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>selectemployee.id,employee.name,department.nameasdepart_namefromemployeeleftjoindepartmentonemployee.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>selectemployee.id,employee.name,department.nameasdepart_namefromemployeerightjoindepartmentonemployee.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*fromemployeeleftjoindepartmentonemployee.dep_id=department.idunionselect*fromemployeerightjoindepartmentonemployee.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unionall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selectemployee.name,department.namefromemployeeinnerjoindepartmentonemployee.dep_id=department.idwhereage>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selectemployee.id,employee.name,employee.age,department.namefromemployee,departmentwhereemployee.dep_id=department.idandage>25orderbyageasc;+----+---------+------+--------------+|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selectid,namefromdepartmentwhereidin(selectdep_idfromemployeegroupbydep_idhavingavg(age)>25);#查看技术部员工姓名selectnamefromemployeewheredep_idin(selectidfromdepartmentwherename='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)selectnamefromdepartmentwhereidnotin(selectdistinctdep_idfromemployee);

（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>selectname,agefromempwhereage>(selectavg(age)fromemp);#查询大于部门内平均年龄的员工名、年龄selectt1.name,t1.agefromempt1innerjoin(selectdep_id,avg(age)avg_agefromempgroupbydep_id)t2ont1.dep_id=t2.dep_idwheret1.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*fromemployeewhereexists(selectidfromdepartmentwhereid=200);#department表中存在dept_id=205，Falsemysql>select*fromemployeewhereexists(selectidfromdepartmentwhereid=204);