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        DML( Data operation language )： Used to manipulate data contained in database objects
                 Include
                        INSERT ( Add data statement )
                        UPDATE ( Update data statement )
                        DELETE ( Delete data statement )

1、 Add data （insert）

grammar ：insert into Table name ( Field 1, Field 2, Field 3, … )values(' value 1', ' value 2', ' value 3',…);

Example 1： towards user Table add data

CREATE TABLE IF NOT EXISTS `user`(
`userId` INT(10) PRIMARY KEY,
`userName` VARCHAR(20) NOT NULL,
`userGender` VARCHAR(1) NOT NULL,
`money` DECIMAL(3,2)
);


# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO `user` (userId,userName,userGender,money)VALUES(1001,'zhangsan',' male ',2.55)
INSERT INTO USER VALUES(1002,'lisi',' male ',2.88)

give the result as follows ：

Example 2： towards student Table add data

（1） Create... As shown in the following table MySQL Realization ：

（2） Code ：

# Create database myschool
CREATE DATABASE myschool;

# Using a database myschool
USE myschool;

# add to student Table data 
CREATE TABLE `student`(
` Student number ` INT(10),
` full name ` VARCHAR(20) NOT NULL,
` Gender ` VARCHAR(1) DEFAULT ' male ' NOT NULL,
` grade ` INT(10) NOT NULL,
` cell-phone number ` VARCHAR(20) NOT NULL,
` Address ` VARCHAR(20) NOT NULL,
` mailbox ` VARCHAR(20) NOT NULL,
` Id card ` VARCHAR(20) NOT NULL,
PRIMARY KEY(` Student number `,` Id card `)
);
DROP TABLE student
INSERT INTO student VALUES(1011,' Guo Jing ',' male ',1,'13500000001',' Zhongguancun Street, Haidian District, Beijing 1 Number ','[email protected]',450323198612111000)
INSERT INTO student VALUES(1012,' Li Wencai ',' male ',2,'13500000002',' Luoyang, Henan ','[email protected]','450323198112311000')
INSERT INTO student VALUES(1013,' Li Mei ',' Woman ',3,'13500000015',' Luwan District, Shanghai ','[email protected]','450323198612311000')

（3） Output results ：

Example 3： towards subject Table add data

（1） Create... As shown in the following table MySQL Realization ：

（） Code ：

# practice 1： Add data 
CREATE TABLE `subject`(
`SubjectNo` INT(10) NOT NULL COMMENT ' Course number ',
`SubjectName` VARCHAR(50) NOT NULL COMMENT ' Course name ',
`ClassHour` VARCHAR(10) NOT NULL COMMENT ' Class hours ',
`GreadID` INT(10) NOT NULL COMMENT ' Grade number ',
PRIMARY KEY(`SubjectNo`)
)

# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO SUBJECT VALUES(1,' Advanced mathematics -1','120',1)
INSERT INTO SUBJECT VALUES(2,' Advanced mathematics -2','110',2)
INSERT INTO SUBJECT VALUES(3,' Advanced mathematics -3','100',3)
INSERT INTO SUBJECT VALUES(4,' Advanced mathematics -4','130',4)

Output results ：

Example 4： Create student table 、 The curriculum 、 Teachers list 、 Grade sheet and insert data

（1） Create... As shown in the following table MySQL Realization

（2） Code ：

# Student list 
CREATE TABLE `student` (
  `s_id` VARCHAR(20),
  `s_name` VARCHAR(20) NOT NULL DEFAULT '',
  `s_birth` VARCHAR(20) NOT NULL DEFAULT '',
  `s_sex` VARCHAR(10) NOT NULL DEFAULT '',
  PRIMARY KEY (`s_id`)
);

# The curriculum 
CREATE TABLE `Course`(
`c_id` VARCHAR(20),
`c_name` VARCHAR(20) NOT NULL DEFAULT '',
`t_id` VARCHAR(20) NOT NULL,
PRIMARY KEY(`c_id`)
);

# Teachers list 
CREATE TABLE `Teacher`(
`t_id` VARCHAR(20),
`t_name`VARCHAR(20) NOT NULL DEFAULT '',
PRIMARY KEY(`t_id`)
);

# League tables 
CREATE TABLE `Score`(
`s_id` VARCHAR(20),
`c_id` VARCHAR(20),
`s_score` INT(3),
PRIMARY KEY(`s_id`,`c_id`)
);

# Insert student table test data 
INSERT INTO student VALUES('01',' Zhao Lei ','1990-01-01',' male ');
INSERT INTO student VALUES('02',' Qian Dian ','1990-12-21',' male ');
INSERT INTO student VALUES('03',' Sun Feng ','1990-05-20',' male ');
INSERT INTO student VALUES('04',' Li Yun ','1990-08-06',' male ');
INSERT INTO student VALUES('05',' Zhou Mei ','1991-12-01',' Woman ');
INSERT INTO student VALUES('06',' Wu Lan ','1992-03-01',' Woman ');
INSERT INTO student VALUES('07',' Zheng Zhu ','1989-07-01',' Woman ');
INSERT INTO student VALUES('08',' Wangju ','1990-01-20',' Woman ');

# Curriculum test data 
INSERT INTO Course VALUES ('01',' Chinese language and literature ','02');
INSERT INTO Course VALUES ('02',' mathematics ','01');
INSERT INTO Course VALUES ('03',' English ','03');

# Teacher table test data 
INSERT INTO Teacher VALUES ('01',' Zhang San ');
INSERT INTO Teacher VALUES ('02',' Li Si ');
INSERT INTO Teacher VALUES ('03',' Wang Wu ');

# Score sheet test data 
INSERT INTO Score VALUES ('01','01',80);
INSERT INTO Score VALUES ('01','02',90);
INSERT INTO Score VALUES ('01','03',99);
INSERT INTO Score VALUES ('02','01',70);
INSERT INTO Score VALUES ('02','02',60);
INSERT INTO Score VALUES ('02','03',80);
INSERT INTO Score VALUES ('03','01',80);
INSERT INTO Score VALUES ('03','02',80);
INSERT INTO Score VALUES ('03','03',80);
INSERT INTO Score VALUES ('04','01',50);
INSERT INTO Score VALUES ('04','02',30);
INSERT INTO Score VALUES ('04','03',20);
INSERT INTO Score VALUES ('05','01',76);
INSERT INTO Score VALUES ('05','02',87);
INSERT INTO Score VALUES ('06','01',31);
INSERT INTO Score VALUES ('06','03',34);
INSERT INTO Score VALUES ('07','02',89);
INSERT INTO Score VALUES ('07','03',98);

（3） Output results

student surface ：

course surface ：

teacher surface ：

score surface ：

Example 5： towards emp Table add data

（1） Create... As shown in the following table MySQL Realization

（2） Code ：

# establish emp surface 
CREATE TABLE emp(
`id` INT(10) NOT NULL COMMENT 'ID', 
`name` VARCHAR(100) NOT NULL COMMENT ' full name ',
`gender` VARCHAR(10) DEFAULT ' male ' NOT NULL COMMENT ' Gender ',
`birthday` DATE COMMENT ' Date of birth ',
`salary` FLOAT(10,2) COMMENT ' salary ',
`entry_date` DATE COMMENT ' Starting time ',
`resume` TEXT COMMENT ' resume ',
PRIMARY KEY(`id`)
);


# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO emp(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(1,'zhangsan','female','1990-5-10',10000,'2015-5-5','good girl')

INSERT INTO emp(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(2,'lisi','male','1995-5-10',10000,'2015-5-5','good boy')

INSERT INTO emp(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(3,'wangwu','male','1995-5-10',10000,'2015-5-5','good boy')

（3） Output results

Example 6： Create database 、 Data sheet , And insert data into the table

（1） Code ：

# Create database examination
CREATE DATABASE IF NOT EXISTS `examination`;

# Using a database examination
USE examination;

# Create a student information table 
CREATE TABLE IF NOT EXISTS `student`(
`sno` VARCHAR(20) NOT NULL PRIMARY KEY COMMENT ' Student number ',
`sname` VARCHAR(20) NOT NULL COMMENT ' full name ',
`ssex` VARCHAR(20) NOT NULL COMMENT ' Gender ',
`sbirthday` DATETIME COMMENT ' Date of birth ',
`class` VARCHAR(20) COMMENT ' class '
);

# Create a teacher information table teacher
CREATE TABLE IF NOT EXISTS `teacher`(
`tno` VARCHAR(20) NOT NULL PRIMARY KEY COMMENT ' Teacher number ',
`tname` VARCHAR(20) NOT NULL COMMENT ' full name ',
`tsex` VARCHAR(20) NOT NULL COMMENT ' Gender ',
`tbirthday` DATETIME COMMENT ' Date of birth ',
`prof` VARCHAR(20) COMMENT ' The title ',
`depart` VARCHAR(20) NOT NULL COMMENT ' section and department '
)

# Create a curriculum 
CREATE TABLE IF NOT EXISTS `course`(
`cno` VARCHAR(20) NOT NULL PRIMARY KEY COMMENT ' Course number ',
`cname` VARCHAR(20) NOT NULL COMMENT ' Course name ',
`tno` VARCHAR(20) NOT NULL COMMENT ' Teacher's teaching number ',
CONSTRAINT fk_course_tno FOREIGN KEY(`tno`) REFERENCES `teacher`(`tno`)
);

# Create a score sheet score 
CREATE TABLE IF NOT EXISTS `score`(
`sno` VARCHAR(20) NOT NULL COMMENT ' Student student id ',
`cno` VARCHAR(20) NOT NULL COMMENT ' Course number ',
`degree` NUMERIC(4,1) COMMENT ' achievement ',
CONSTRAINT fk_score_sno FOREIGN KEY (`sno`) REFERENCES `student`(`sno`),
CONSTRAINT fk_score_cno FOREIGN KEY (`cno`) REFERENCES `course`(`cno`)
);

# To the students student Table add data 
# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(108,' Zeng Hua ',' male ','1977-09-01','95033');
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(105,' Kuang Ming ',' male ','1975-10-02','95031');
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(107,' Wang Li ',' Woman ','1976-01-23','95033');
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(101,' Li Jun ',' male ','1976-02-20','95033');
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(109,' Wang Fang ',' Woman ','1975-02-20','95031');
INSERT INTO student(sno,sname,ssex,sbirthday,class)VALUES(103,' Lu Jun ',' male ','1974-06-03','95031');

# Information to teachers teacher Table add data 
INSERT INTO teacher(tno,tname,tsex,tbirthday,prof,depart)VALUES(804,' Li Cheng ',' male ','1958-12-02',' associate professor ',' Department of Computer Science ');
INSERT INTO teacher(tno,tname,tsex,tbirthday,prof,depart)VALUES(856,' Zhang Xu ',' male ','1969-03-12',' lecturer ',' Department of electronic engineering ');
INSERT INTO teacher(tno,tname,tsex,tbirthday,prof,depart)VALUES(825,' Wang Ping ',' Woman ','1972-05-05',' Assistant ',' Department of Computer Science ');
INSERT INTO teacher(tno,tname,tsex,tbirthday,prof,depart)VALUES(831,' Liu Bing ',' Woman ','1977-08-14',' Assistant ',' Department of electronic engineering ');

# To the course course Table add data 
INSERT INTO course(cno,cname,tno)VALUES('3-105',' Introduction to computer ',825);
INSERT INTO course(cno,cname,tno)VALUES('3-245',' operating system ',804);
INSERT INTO course(cno,cname,tno)VALUES('6-166',' digital circuit ',856);
INSERT INTO course(cno,cname,tno)VALUES('9-888',' Advanced mathematics ',831);

# To the result score Table add data 
INSERT INTO score(sno,cno,degree)VALUES(103,'3-245',86);
INSERT INTO score(sno,cno,degree)VALUES(105,'3-245',75);
INSERT INTO score(sno,cno,degree)VALUES(109,'3-245',68);
INSERT INTO score(sno,cno,degree)VALUES(103,'3-105',92);
INSERT INTO score(sno,cno,degree)VALUES(105,'3-105',88);
INSERT INTO score(sno,cno,degree)VALUES(109,'3-105',76);
INSERT INTO score(sno,cno,degree)VALUES(101,'3-105',64);
INSERT INTO score(sno,cno,degree)VALUES(107,'3-105',91);
INSERT INTO score(sno,cno,degree)VALUES(108,'3-105',78);
INSERT INTO score(sno,cno,degree)VALUES(101,'6-166',85);
INSERT INTO score(sno,cno,degree)VALUES(107,'6-166',79);
INSERT INTO score(sno,cno,degree)VALUES(108,'6-166',81);

（2） Output results

student surface ：

teacher surface ：

course surface ：

score surface ：

2、 Modifying data (update)

grammar ：update Table name set [ Field name 1= The new data 1, Field name 2= The new data 2,...][where condition]
where Conditional clause ： Conditionally filter data from the table
where Operator in ：
surface Operator
Operator meaning Example result
= be equal to 5=6 false
<> or != It's not equal to 5!=6 true
> Greater than 5>6 false
< Less than 5<6 true
>= Greater than or equal to 5>=6 false
<= Less than or equal to 5<=6 true
between In a certain range BETWEEN 5 AND 10 -
AND also 5>1 AND 1>2 false
OR or 5>1 OR 1>2 true

surface Operator
Operator	meaning	Example	result
=	be equal to	5=6	false
<> or !=	It's not equal to	5!=6	true
>	Greater than	5>6	false
<	Less than	5<6	true
>=	Greater than or equal to	5>=6	false
<=	Less than or equal to	5<=6	true
between	In a certain range	BETWEEN 5 AND 10	-
AND	also	5>1 AND 1>2	false
OR	or	5>1 OR 1>2	true

Example 7： modify emp1 The data in the table

（1） establish emp1 surface , Parallel table emp1 insert data

（2） After inserting data , Modify the data ：

# establish emp1 surface 
CREATE TABLE emp1(
`id` INT(10) NOT NULL COMMENT 'ID', 
`name` VARCHAR(100) NOT NULL COMMENT ' full name ',
`gender` VARCHAR(10) DEFAULT ' male ' NOT NULL COMMENT ' Gender ',
`birthday` DATE COMMENT ' Date of birth ',
`salary` FLOAT(10,2) COMMENT ' salary ',
`entry_date` DATE COMMENT ' Starting time ',
`resume` TEXT COMMENT ' resume ',
PRIMARY KEY(`id`)
);
#------------------------------------------------------------------------------------------
# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO emp1(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(1,'zhangsan','female','1990-5-10',10000,'2015-5-5','good girl')

INSERT INTO emp1(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(2,'lisi','male','1995-5-10',10000,'2015-5-5','good boy')

INSERT INTO emp1(id,NAME,gender,birthday,salary,entry_date,RESUME)
VALUES(3,'wangwu','male','1995-5-10',10000,'2015-5-5','good boy')

#------------------------------------------------------------------------------------------
# Modify the data in the table 
# grammar ：update  Table name  set  Field name 1= The new data 1, Field name 2= The new data 2,...where....
# Change all employee salaries to 5000 element 
UPDATE emp1 SET salary=5000

# Name is “zhangsan” The salary of the employee is revised to 3000
UPDATE emp1 SET salary = 3000 WHERE `name`='zhangsan';

# Name is “lisi” The salary of the employee is revised to 4000 element ,gender Change it to female
UPDATE emp1 SET salary=4000,gender='female' WHERE `name`='lisi';

# take wangwu My salary is increased on the original basis 1000 element 
UPDATE emp1 SET salary=salary+1000 WHERE `name`='wangwu';

（3） Output results

① Change all employee salaries to 5000 element

② Name is “zhangsan” The salary of the employee is revised to 3000

③ Name is “lisi” The salary of the employee is revised to 4000 element ,gender Change it to female

④ take wangwu My salary is increased on the original basis 1000 element

Example 8： Change the student number (StudentNo) by 1013 Student records of
         modify student Table data
         Use update Statement modification student Table data
         Change the student number (StudentNo) by 1013 Student records of
        （1） Change the email address to [email protected]
        （2） cell-phone number （phone） It is amended as follows 000000
（1） Create database 、 Data sheet , And insert the data as follows ：
（2） Use update Statement modification student Table data ：
（3） Output results
① Matrikl-Nr (StudentNo) by 1013 The student email of is modified to [email protected]

② Matrikl-Nr (StudentNo) by 1013 Student mobile number （phone） It is amended as follows 000000

Example 9： Modification example 3 Medium subject Table data

Requirement specification ：

Put the data sheet subject in ClassHour Greater than 110 And GradeID by 1 Class hours are reduced 10

（1） Example 3 Created subject The table is shown below ：

（2） Put the data sheet subject in ClassHour Greater than 110 And GradeID by 1 Class hours are reduced 10

# practice 1： Add data 
CREATE TABLE `subject`(
`SubjectNo` INT(10) NOT NULL COMMENT ' Course number ',
`SubjectName` VARCHAR(50) NOT NULL COMMENT ' Course name ',
`ClassHour` VARCHAR(10) NOT NULL COMMENT ' Class hours ',
`GreadID` INT(10) NOT NULL COMMENT ' Grade number ',
PRIMARY KEY(`SubjectNo`)
);

# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO SUBJECT VALUES(1,' Advanced mathematics -1','120',1);
INSERT INTO SUBJECT VALUES(2,' Advanced mathematics -2','110',2);
INSERT INTO SUBJECT VALUES(3,' Advanced mathematics -3','100',3);
INSERT INTO SUBJECT VALUES(4,' Advanced mathematics -4','130',4);

# grammar ：update  Table name  set  Field name 1= The new data 1, Field name 2= The new data 2,...where....
# Put the data sheet subject in ClassHour Greater than 110 And GradeID by 1 Class hours are reduced 10
UPDATE SUBJECT SET classHour=classHour-10 WHERE classHour>110 AND GreadID=1;

（3） Output results ：

3、 Delete data (delete)

grammar ：delete from Table name [where condition]
condition Filter by , If not specified, delete all data of the table

Example 10： Delete example 3 Medium subject Table data

（1） Example 3 Created subject The table is shown below ：

（2） Code ：

# Use delete Statement delete data 
# grammar ：delete from  Table name  [where condition]
#-------------------------------------------------------
# Create table 
CREATE TABLE `subject1`(
`SubjectNo` INT(10) NOT NULL COMMENT ' Course number ',
`SubjectName` VARCHAR(50) NOT NULL COMMENT ' Course name ',
`ClassHour` VARCHAR(10) NOT NULL COMMENT ' Class hours ',
`GreadID` INT(10) NOT NULL COMMENT ' Grade number ',
PRIMARY KEY(`SubjectNo`)
);

#-------------------------------------------------------
# Use insert Statement to user Add data to the table 
# grammar ：insert into  Table name (  Field 1,  Field 2,  Field 3, … )values(' value 1', ' value 2', ' value 3',…);
INSERT INTO SUBJECT1 VALUES(1,' Advanced mathematics -1','120',1);
INSERT INTO SUBJECt1 VALUES(2,' Advanced mathematics -2','110',2);
INSERT INTO SUBJECT1 VALUES(3,' Advanced mathematics -3','100',3);
INSERT INTO SUBJECT1 VALUES(4,' Advanced mathematics -4','130',4);

#-------------------------------------------------------
# Use delete Statement delete data 
# grammar ：delete from  Table name  [where condition]

#(1)condition Filter by , If not specified, delete all data of the table 
DELETE FROM subject1;

#(2) Delete subject1 In the table GreadID Greater than 2 The data of 
DELETE FROM subject1 WHERE GreadID>2;

（3） Output results

①condition Filter by , If not specified, delete all data of the table

② Delete subject1 In the table GreadID Greater than 2 The data of

4.DDL( Data definition language ) and DML( Data operation language ) Comprehensive case

Example 11： Create an employee table , And modify the table information and the data in the table
（1） subject ：
        1. Create an employee table
Field attribute
id plastic （int）
name character string (varchar)( The length is 20)
gender character string ( The length is 2)
birthday Date type (date)
email character string ( The length is 10)
remark character string ( The length is 50)
        2. Revise the table exercise
                2.1 Add age Column
                2.2 modify email The column length is 50
                2.3 Delete remark Column
                2.4 Name name It is amended as follows username
        3. Practice adding, deleting and modifying data on the employee table
                3.1 Add data
                3.2 Modifying data ： take id by 4 Of that line username Change it to “ Frisa ”
                3.3 Delete data ： Delete age by 2000 That line
                3.4 Modifying data ： take id by 4 Of that line age Set to 250
                3.5 Modifying data ： take id by 5 Of that line username Change it to “ The Monkey King ”, Change the age to 26
（2） The code is as follows ：
#1. Create an employee table workers
DROP TABLE workers;
CREATE TABLE `workers`(
`id` INT(10) PRIMARY KEY AUTO_INCREMENT,
`name` VARCHAR(20) NOT NULL,
`gender` VARCHAR(2) NOT NULL,
`birthday` DATE NOT NULL,
`email` VARCHAR(10) NOT NULL,
`remark` VARCHAR(50) NOT NULL
)

#------------------------------------------------------
#2. Modify table information 
#2.1  Add age Column 
# grammar ：ALTER TABLE  Table name  ADD  Field name   Column type [ attribute ]
ALTER TABLE workers ADD age INT(100) NULL;

#2.2  modify email The column length is 50
/* grammar ： Both can be used , Often use the second 
 *(1)ALTER TABLE  Table name  MODIFY  Field name   Column type [ attribute ]
 *(2)ALTER TABLE  Table name  CHANGE  Old field name   new field name   Column type [ attribute ]
 */
#ALTER TABLE workers MODIFY email varchar(50);
ALTER TABLE workers CHANGE email email VARCHAR(50);

#2.3  Delete remark Column 
# grammar ：ALTER TABLE  Table name  DROP  Field name 
ALTER TABLE workers DROP remark;

#2.4  Name name It is amended as follows username
# grammar ：ALTER TABLE  Table name  CHANGE  Old field name   new field name   Column type [ attribute ]
ALTER TABLE workers CHANGE NAME username VARCHAR(20);

#-------------------------------------------------------
#3. Practice adding, deleting and modifying data on the employee table 
#3.1  Add data 
INSERT INTO workers VALUES(1,' Zhang Sanfeng ',' male ','1367-10-21','[email protected]',102);
INSERT INTO workers VALUES(2,' dharma ',' male ','1227-4-15','[email protected]',54);
INSERT INTO workers VALUES(3,' Mei Chaofeng ',' Woman ','1547-6-1','[email protected]',44);
INSERT INTO workers VALUES(4,' Trisomy ',' Unknown ','3012-8-15','[email protected]',2000);
INSERT INTO workers VALUES(5,' Super Saia ',' male ','1985-2-3','[email protected]',25);

#3.2  Modifying data ： take id by 4 Of that line username Change it to “ Frisa ”
# grammar ：UPDATE  Table name  SET  Field name 1= The new data , Field name 2= The new data ,... ...WHERE... ...
UPDATE workers SET username=' Frisa ' WHERE id=4;

#3.3  Delete data ： Delete age by 2000 That line 
DELETE FROM workers WHERE age=2000;

#3.4  Modifying data ： take id by 4 Of that line age Set to 250
# grammar ：UPDATE  Table name  SET  Field name 1= The new data , Field name 2= The new data ,... ...WHERE... ...
# This is used to supplement the deleted data above ：
#INSERT INTO workers VALUES(4,' Frisa ',' Unknown ','3012-8-15','[email protected]',2000);
UPDATE workers SET age=250 WHERE id=4;

#3.5  Modifying data ： take id by 5 Of that line username Change it to “ The Monkey King ”, Change the age to 26
# grammar ：UPDATE  Table name  SET  Field name 1= The new data , Field name 2= The new data ,... ...WHERE... ...
UPDATE workers SET username=' The Monkey King ',age=26 WHERE id=5;
（3） Output results ：
        1. Create an employee table
         2. Revise the table exercise
                2.1 Add age Column

                2.2 modify email The column length is 50

                2.3 Delete remark Column

                2.4 Name name It is amended as follows username

        3. Practice adding, deleting and modifying data on the employee table
                3.1 Add data

                3.2 Modifying data ： take id by 4 Of that line username Change it to “ Frisa ”

                3.3 Delete data ： Delete age by 2000 That line

                3.4 Modifying data ： take id by 4 Of that line age Set to 250

                3.5 Modifying data ： take id by 5 Of that line username Change it to “ The Monkey King ”, Change the age to 26

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2. MySQL data management - DML (add, modify, delete data)

01、DML（ Data operation language ）

1、 Add data （insert）

Example 1： towards user Table add data

Example 2： towards student Table add data

Example 3： towards subject Table add data

Example 4： Create student table 、 The curriculum 、 Teachers list 、 Grade sheet and insert data

Example 5： towards emp Table add data

Example 6： Create database 、 Data sheet , And insert data into the table

2、 Modifying data (update)

Example 7： modify emp1 The data in the table

Example 8： Change the student number (StudentNo) by 1013 Student records of

Example 9： Modification example 3 Medium subject Table data

3、 Delete data (delete)

Example 10： Delete example 3 Medium subject Table data

4.DDL( Data definition language ) and DML( Data operation language ) Comprehensive case

Example 11： Create an employee table , And modify the table information and the data in the table

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Field	attribute
id	plastic （int）
name	character string (varchar)( The length is 20)
gender	character string ( The length is 2)
birthday	Date type (date)
email	character string ( The length is 10)
remark	character string ( The length is 50)