Chapter One Data Model
Goal :
1. The concept of database
2. What is a database management system? What is RDBMS ?
DBMS:database Management System
RDBMS:Relationship DBMS
Object-based logical model :
3. What is the ER diagram? Entity - relationship model ; power designer can design ER diagrams
The concept of entity :
Concept of relationship :
4. How many kinds of relationships are there between entities ? What are the differences? Three types : 1:1; 1:N; M:N
Log-based model:
1. Three model types
2. The basic storage structure of the relational model is a table
3. Tuples ( records ) , attributes ( fields )
4. Primary key : uniquely identifies a tuple (one row)
5.Master- slave table ( parent-child table ), foreign key
6. Eight operators
operation:
1. established between teachers, students, grades, courses ER diagram , requires entities, relationships, attributes (3 Ge ) , weak entity
2. What are the primary key and foreign key?
3. Give an example of each of the eight major relationships .
Expansion:
1. Pick a few entities in the QQ space, identify the attributes of the entities, and establish the relationship between the entities, there must be (1:1,1:m,m:n)