Task 1, tóm tắt DBMS

1. General Definition:
- Data: a record of operation generated daily contain information that is already done.
- Database: is a collection of data that is gathered and analyzed for many purposes.
- Data Management: analyzing and organizing large amount of information. DM has 2 basic types:
  + File Based system.
  + Data based system.
2. File based system: a system of analyzing and organizing data by files:
- It’s difficult to standardize file of data -> data file will be inconsistent.
- It’s hard to query: means it’s difficult to analyze a large amount of files.
- The relation among files is too week.
3. Data based system:
- Use to store a data as a record of system.
- It is organized logically and interactively with strong relation to each others.
- By logically arranged, Database system can save and reduce storage of data.
- Well organized provided user an easier way to access data.
- Data in database system is located with a specific standard so it is more consistent than file based system.
4. Database Management System: DBMS:
- Not only the management of records. DBMS provide a set of program that allows users managing data ( records) like: entering, storing and exporting ….
- Basically, the DBMS products can differ for matching users purposes.
- It supports different kind of query data like: Structured Query Language (SQL)… or Four Generation Language ( 4GLs).
- DBMS software also provide a access way for end-user to accessing and managing data from database.
- By processing large data, DBMS provide a tool to collect and analyze data for getting value information from database:
- Storing data tools.
- Define and Structure Data ( records).
- Data I/O management.
- Data Security and recovery.
- Optimize query allow user to have the best performance when managing database system.
- Multi-user access.
- Application Programming Interfaces ( API).
5. Database Models:
- Flat File Data Model: Database only contain one table or file: simple model.
- Hierarchical Model:  a kind of TREE structure database.
- Network data model: wider than Hierarchical Model, Network data model provide an exception of relation between children and parents: children can be inside of many parents.
- Relational Data Model: All data stored in form of table with rows and columns, and tables related to others by common columns, not physical links.
6. Relational Database Management System:
 - In order to simplify the database system, RDBMS divided units into simple logical units: tables.
- Relational database is a database structured on relational model.
- Terms related to RDBMS:
- Data is presented as a collection of relations.
- Each relation is depicted as a table.
- Columns are attributes.
- Rows represent entities.
- Every table has a set of attributes that are taken together as a ‘key’ (technically, a ‘superkey’),
which uniquely identifies each entity.
- RDBMS Users:
- Administrator – DBA: authorizing access to DB and monitoring it.
- Database Designer: choosing suitable structures for storing date due to user’s purpose.
- System analysts and Application Programmer: Define user requirement and implement it.
- DBMS Designers and Implementer.
- End User.
7. Entities and tables:
- Entity: is the information that can be distinct. Entity normally stored in rows.
- Each Entity has a certain attributes ( defined by columns).
a group of related entities is an entity set.
- Tables: defined by rows and columns. Row known as tuple and columns as attributes.