Database course design of online assistant teaching platform for high school chemistry

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The design of high school chemistry online assistant teaching platform can provide students with a resource sharing 、 Interactive and collaborative teaching environment , Provide students with a flexible way to learn . The main functions of the system are ： Realize the unified management of courses , Student 、 Teachers' basic information management , Release of teaching resources 、 download 、 see 、 Browsing and online teacher guidance and Q & A functions . This design mainly carries out the demand analysis 、 Database design 、 Data manipulation, etc .

One 、 Project description

1.1 Content of course design

This course design is to design a teaching platform for online tutoring of high school chemistry courses , So that it can provide a resource sharing for high school chemistry curriculum 、 Interactive and collaborative teaching environment , Provide students with a flexible way to learn . The system should realize the unified management of courses , Student 、 Teachers' basic information management , Release of teaching resources 、 download 、 see 、 Browsing and online teacher guidance and Q & A functions .

1.2 The purpose of curriculum design

Database has become the foundation of the whole information society , And database technology as IT One of the fastest growing technologies in all walks of life , It has been widely used in various types of data processing systems . Apply database technology to online course guidance platform , It will greatly improve the efficiency of the management platform , Reduce management pressure .
On the one hand, this database course design can make you more familiar with the basic steps of database system design , Master data flow diagram and E—R The design idea of the diagram , And how to transform conceptual model into relational model , On the other hand , It also allows us to learn by ourselves SQL Statement create database 、 Tables and methods of operating databases .

Two 、 Demand analysis

2.1 functional requirement

In recent years , With the normalization of the epidemic , Online teaching is becoming more and more popular , High school chemistry is an important course in science , It is necessary to establish a database management platform for teachers 、 Student 、 Teaching resources and other information management , The object of the online auxiliary teaching platform of high school chemistry curriculum is high school students and high school chemistry teachers , Therefore, these two aspects are mainly considered in the demand analysis . For the majority of students , The most important thing is to easily browse the information you want and communicate with teachers ; secondly , For teachers , Mainly responsible for uploading course resources and answering questions . In order to ensure the continuous updating of resource information , Therefore, the administrator role is set in the background , It is used to maintain resources in the Group .
The main functions of this system are as follows ：
(1) Student information management ： Provide student information maintenance function , It mainly provides the input of student information 、 modify 、 Delete function , At the same time, provide students with courses to learn , Questions and questions , View reply , Resource download and other functions .
(2) Teacher information management ： Provide teacher information management function , It mainly provides the input of teacher information 、 modify 、 Delete function , At the same time, it provides teachers with the ability to check questions , Post reply , Resources upload and other functions
(3) Course information management ： Provide course information maintenance function , It mainly provides the entry of course information 、 modify 、 Delete function .
(4) Resource information management ： Provide resource information maintenance function , It mainly provides the input of resource information 、 modify 、 Delete function .
(5) Problem information management ： Provide problem information maintenance function , It mainly provides problem entry 、 modify 、 Delete function .
(6) Question reply management ： Provide question reply maintenance function , It mainly provides the input of question reply 、 modify 、 Delete function .

2.2 Data flow analysis

2.2.1 Tools for data flow analysis

Data flow diagram （DFD） It's a kind of graphic technology , It depicts the transformation of information flow and data from input to output . There are no specific physical elements in the data flow diagram , It just describes the flow and processing of information in the system , The four basic symbols and specific descriptions of the data flow diagram are shown in Figure 2.1 Shown .

chart 2.1 Basic symbols of data flow diagram
The main role of data flow diagram in system analysis is reflected in the following points ：
1） Data flow diagram is a graphic representation of system logic functions , It's easy for non professional computer personnel to understand it , So it is an excellent communication tool between analysts and users .
2) Data flow diagram can clearly describe the flow of data in the system and the logical process being processed .
3） Data flow diagram is a graphic representation of system logic functions , Easy to understand .

2.2.2 System data flow diagram

Through analysis , The foreground data flow diagram of this system is shown in 2.2-2.4 Shown .

chart 2.2 The front desk 0 Layer data flow graph

2.2.3 The data dictionary

The data dictionary （DD,Data Dictionary） It is recorded in a specific format 、 The basic elements in the data flow chart of the system （ Data flow 、 machining 、 Storage and external items ） A complete definition and description of the content and characteristics of . The data dictionary is an important supplement and explanation to the data flow chart . There are five types of entries in the data dictionary ： External entities 、 Data flow 、 data storage 、 Data items and processing .
The data dictionary includes data definitions , But besides it , It also contains some other information . General information , Including the name 、 Aliases and descriptions . For the above data flow diagram , Give a description of some items .

(1) Teacher information
Data stream name ： Teacher information
Alias ：
describe ： Define the basic information of teachers
form ： Teacher information = Teacher number + cell-phone number + Gender + email + Address + The title + full name
remarks ：
(2) Course information
Data stream name ： Course information
Alias ：
describe ： Defines course information
form ： Course information + Course name + Course introduction + teaching program
remarks ：
(3) Teaching resource information
Data stream name ： Teaching resource information
Alias ：
describe ： Defines the information of teaching resources
form ： Teaching resource information = Resource number + Resource name + Upload date + Course number
remarks ：

3 Database design

3.1 Database conceptual structure design
Conceptual structure design is the process of abstracting user requirements obtained from system requirements analysis into information structure reflecting user views . The result of conceptual structure design is the conceptual model of database , That is E-R Model . Because it is abstracted and described from the perspective of the real world , So it is related to computer hardware 、 Database logical structure and support database DBMS irrelevant . Attention should be paid to conceptual structure design in database design , It is the key of the whole database design , It is to prepare the computer for storing data .
The object of this system is high school students and physics teachers , Therefore, these two aspects are mainly considered in the demand analysis . For the majority of students , The most important thing is to easily browse the information you want and communicate with teachers ; secondly , For teachers , Mainly responsible for uploading course resources and answering questions . In order to update the resources of the system in time , The administrator role is set in the background , Its important work is the unified management of the curriculum , And maintain the information of all teachers and students . According to the above requirements, the entities of the system are determined, including courses 、 Teachers' 、 Student 、 Teaching resources 、 Student questions 、 Reply to questions , The attribute diagram of each entity is shown in Figure 3.1-3.6 Shown

3.2 Database logical structure design

E-R The conceptual model represented by figure is the formalization of user data requirements .E-R Graph is a conceptual information structure independent of any data model , Nor for any one DBMS Supported by the . The task of logical structure design is to design a good conceptual structure E-R The diagram is transformed into a specific DBMS The logical structure of the supported data model , The result of the design is a set of relational patterns .
In this system, figure 3.7 Database E-R The diagram is transformed into a relational model as follows ：
Course ( Course number , Course name , Course introduction , teaching program , Teacher number )
Teachers' ( Teacher number , full name , Gender , The title , cell-phone number , email , Address ,)
Student ( Student number , full name , Gender , cell-phone number , email , Date of admission )
Teaching resources （ Resource number , Resource name , Resource content , Course number , Teacher number , Upload date ）
Student questions （ Question number , title , Content , Course number , Student number , Date of question ）
Reply to questions （ Reply message number , Reply content , Question number , Teacher number , Reply date ）

3.3 Database physical structure design

4 Operation of database

4.1 Database creation

use master
go
if exists (select * from sysdatabases where name=' Chemistry course online teaching platform ')
drop database  Chemistry course online teaching platform 
go
create database  Chemistry course online teaching platform 
on primary
( name= Chemistry course online teaching platform _data,
filename='D:\SQLServer2012\ Chemistry course online teaching platform _data.mdf',
size=100MB,
maxsize=200GB,
filegrowth=10%)
log on
( name = Chemistry course online teaching platform _log,
filename='D:\SQLServer2012\ Chemistry course online teaching platform _log.ldf',
size=100MB,
maxsize=200GB,
filegrowth=5%
) 
 Create an online teaching database of high school chemistry courses （HXJX）
create database HXJX

 Create a teacher information table (teacher)
use HXJX
create table teacher(
tno nchar(11) primary key not null , 
tname varchar(20) not null ,
tsex varchar(20) not null,
level varchar(10) not null,
tphone nchar(11) not null,
tmail varchar(20) not null,
taddress varchar(100) not null, 
constraint a1 check(tsex in (' male ',' Woman ')),
)
 Create a student information table (student)
use HXJX
create table student (
sno nchar(11) primary key not null, 
sname varchar(20) not null , 
ssex varchar(4) not null, 
sdate datetime , 
smail varchar(20) ,
saddress varchar(100),  
sphone nchar(11),
constraint a2 check(ssex in (' male ',' Woman ')),
)
........
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summary

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