Oracle Foundation <1>--Database Design

One: Why you need to use database design

Database design enables the database to work efficiently and healthily through a robust database structure.

two. Database design principles ( database design, system design, architecture design)

1. Familiarity with requirements

Ensure that changes in requirements will not affect database maintenance, updates, and reduced work costs

2. Develop a database that conforms to the specification

(1). Naming conventions

(2). Clarifying the relationship between real-world entities and data tables

· (3). A data table cannot have neither a primary key nor a foreign key (the primary key is an abstraction of a real entity, and a foreign key represents a relationship between entities in reality)

(4). Characteristics of the basic table

Atomicity: The fields in the base table are not decomposed

Primitive: Records in the base table are records of the original data

Deductive: The basic tables and relational tables can derive any desired data

Stability: The structure in the base table is relatively stable, and the records in the table need to be saved for a long time

(5). Must satisfy the first second normal form, as far as possible to meet the third paradigm ( attribute atomicity constraints, the uniqueness of the record constraints, the constraints of field redundancy )

(6). To have a concise E-r diagram: simple entities, diagrams

(7). To comply with integrity constraints

3. Audit Database Design

Three. Data model

1. Relational model E-r diagram: Designing a database through relationships between entities

2. Object model or:

Four. Techniques for database design

(1). table Three less : In line with the requirements of the system, the fewer tables the better, the less the number of fields in a table, the better the fewer fields in a table, the better

(2). Check various change fields

(3). Avoid using reserved words

(4). Delete a tag field

(5). Avoid using triggers

(6). If you find re-entering data, you need to create a new table and a new relationship

(7). Skilled use of database design tools

(8). Create E-r icons and data dictionaries

(9). Each table should be UF 3 useful fields: Modify record time, modified person, modified version

(10). Use multiple fields for address and phone

(11). Handle many-to-many relationships correctly

Five. Steps for database design

(1). Mobile Information

(2). Identifying Objects

(3). Building an object model

(4). Indicate the type of information each object needs to store

(5). Represents the relationship between objects

Oracle Foundation <1>--Database Design