Basic theory of oracle database

Oracle database basic theory is a collection of basic knowledge and concepts for understanding and operating Oracle databases, including: core principles of database management systems: data abstraction, consistency, persistence, concurrency database design: entity relationship model, logical model, physical model data type: numeric type, character type, date and time type, LOB type index: B tree index, hash index, bitmap index constraints: master key, external key, unique constraint, non-empty constraint security measures: user authentication, authorization, auditing, encryption

What is the basic theory of Oracle database?

The basic theory of Oracle database is a collection of basic knowledge and concepts for understanding and operating Oracle databases. It involves the core principles of database management systems, database design, data types, indexes, constraints and security measures.

Core principles of database management system

• Data abstraction: Separate data from the programs that access data, thereby improving data independence and flexibility.
• Consistency: Ensure that all data in the database is always accurate and consistent.
• Persistence: Data is stored permanently and will not be lost even if the database is shut down or the system failure occurs.
• Concurrency: Allows multiple users to access and update data at the same time without data corruption.

Database Design

• Entity Relationship Model: A model that describes real-world entities and their interrelationships.
• Logical model: a data structure representation independent of physical implementation.
• Physical Model: How to store data in representations on physical devices.

Data Type

• Number type: Stores numeric data such as integers, floating point numbers, and decimals.
• Character type: Stores text data, such as strings and characters.
• Date and Time Type: Stores date, time and timestamp data.
• LOB Type: Stores large objects such as images and documents.

index

• B-tree index: A balanced tree used to quickly find data.
• Hash index: Use hash function to quickly find data.
• Bitmap index: A bit vector used to quickly find data of a specific value.

constraint

• Master Key: Uniquely identifies the columns that each row in the database.
• External key: Connect one table to a column in another table.
• Unique constraint: Make sure that the values ​​in the table are unique.
• Non-empty constraint: Ensure that the values ​​of columns in the table are not empty.

Safety measures

• User Authentication: Verify the user's identity to access the database.
• Authorization: Grants users permission to access specific data and perform specific actions.
• Audit: Record database activity to detect suspicious behavior.
• Encryption: Protect data from unauthorized access.

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