Dependence

Sensibility

Transitivity

Sharability

Timeliness

Data and meaning are inseparable

Data can be expressed in many forms

Data has types and values

The data is subject to constraints such as type value range, etc., and can be divided into qualitative and quantitative

Collect, manage, store, process and disseminate data, etc.

Information = data data processing

Classification

organize

coding

storage

Search

maintain

Data is not retained

No dedicated data management software

There is no independence between data and programs

Data is not shared

Data can be saved for a long time

File system manages data

There is low independence between program and data

Poor data sharing

Data files are diverse

Data structuring

High data sharing

There is a high degree of independence between data and programs

Unified data management and control

Integration

Sharability

database administrator

Database application developer

software

hardware

Also called submode or user mode

Located at the outermost layer of the three-level model

Effective measures to ensure data security

Also known as conceptual pattern and logical pattern

Description of all data logical structures and characteristics

Also known as storage mode or physical mode

How data is represented within the database

There is only one internal schema in a database, which is the physical basis for data access.