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# System prepended metadata

title: ItC Week 15 - Database
tags: [Intro_to_Comp]

---

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# ItC Week 15 - Database

###### tags: `Intro_to_Comp`

## DBMS

- "DataBase Management Software"
- A software to store, access, manage datas, so that applications don't need to worry about it
- Store large amount of data over long peroid of time
- Handle data queries and updates
- Protect data
  - unauthorized access
  - system crashes
  - invalid inputs
- Support multi-user concurrent access
  - 10000 users accessing a site
- Data schema
- Efficient operations
- DDL - Data Definition Language
- DML - Data Manipulation Language

## Level of Abstraction

- Views
- Conceptual schema
- Physical schema

## Relational Model

- Most widely used model
- Simple
- Schema & Instance
  - like class & obj in OOP



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