1. An Overview of Database Management

2. An Example A database system Database Tables, records, SQL Operations
A computerized record-keeping system
Database
A repository for a collection of computerized data files
A kind of electronic filing cabinet
Tables, records, SQL
Operations
Add, insert, retrieve, update, delete, remove
※Repository: 저장소, operation: 연산

3. The wine cellar database

4. Retrieval 검색 SELECT WINE, BIN#, PRODUCER FROM CELLAR WHERE READY=2000;
Cab.Sanvignon 43
Windsor
Pinot Noir 51
Stemmler
Merlot 58
Clos Du Bois

5. Insert, update, delete 삽입, 갱신, 삭제
INTO CELLAR(BIN#, WINE, PRODUCER, YEAR, BOTTLES, READY)
VALUES(53, ‘Pinot Noir’, ‘Saintsbury’, 1997, 6, 2001)
UPDATE CELLAR
SET BOTTLES =4
WHERE BIN# = 3;
DELETE
FROM CELLAR
WHERE BIN# = 2;

6. What is a database system?
A computerized record-keeping system
Components
Data
H/W
S/W
Users
※Record-keeping: 기록유지관리

7. Data in database system
Integrated
Unification of several distinct files
Ex) student files, book files
Shared
Being shared among different users with different purposes
Ex) book tables among students and librarians
※Integrated: 통합된, Shared: 공유된

8. H/W in database system Secondary storage devices – disk
Processor(s) and main memory to support the execution of the database system S/W
※secondary storage device: 이차저장장치

9. S/W in database system DBMS(database management system)
Also known as
database manager
Database server
The shielding of database users from hardware-level details
Ex) Microsoft ACCESS, Microsoft SQL Server, MySQL, ORACLE, DB2, SQLite…
※shield: 방패

10. Users in database system
Application programmers
Write database application programs in some programming language such as C, C++, Java, Visual Basic, COBOL, …
End users
Use the system online thru interface
Interface
Built-in query language processor
Command-driven interfaces
Menu- or forms-driven interfaces
DBA (database administrator)
Creates and maintains database

11. What is a database? Database
A collection of shared persistent data used by the application systems of some particular enterprise
Persistent data
Data that live long time
Differ from short-lived data like input data, output data, intermediate results---transient in nature
※intermediate: 중간의

12. Example A manufacturing company – product data A bank – account data
A hospital – patient data
A university – student data
A government department – planning data

13. Entities and relationships 개체, 관계성
A medium to represent database for an enterprise conceptually.
Entities
Independent, distinguishable objects
Relationship
Unary
Binary
Ternary
※unary:일진, Binary:이진, ternary:삼진

14. Example of E/R A manufacturing company: KnowWare Inc.
Wants to record data about
The projects on hand
The parts used in the projects
The suppliers who supply the parts
The warehouses in which those parts are stored
The employees who work on the projects
 entities

15. Example of E/R
There are relationships linking entities - bidirectional
SP (suppliers and parts)
Each supplier supplies certain parts
Each part is supplied by certain suppliers
PJ (projects and parts)
Parts are used in projects
Projects use parts
WP (warehouse and parts)
Parts are stored in warehouses
Warehouses store parts
※Bidirectional: 양방향의

16. Ex) SP relationship *given a supplier, get the parts supplied by that supplier *given a part, get the suppliers who supply that part
Entity/relationship diagram (E/R diagram for short)

17. Properties
Entities and relationships can be regarded as having properties corresponding to the data we wish to record about them
Ex) suppliers: name, city, …
※property: 특성

18. Why database? Advantages over paper-based method of record keeping
Compactness
No need for voluminous paper files
Speed
Less drudgery
Elimination of maintaining files by hand
Currency
Accurate, up-to-date information
Centralized control in multi-user environment
※drudgery: 힘들고 반복적인 일, currency: 최신

19. Benefits of database Data sharing Reduction of redundancy
Not only existing applications but also new applications
Reduction of redundancy
Integration by DBA
Controlled redundancy
Avoidance of inconsistency
Corollary of reduction of redundancy
※Redundancy: 중복성, corollary: 계, 당연한 결론

20. Benefits of database Transaction support
Transaction: a logical unit of work
Ex) transfer of money from account A to B
Account A and B have to be updated
What if crash occurs before update of account B?
※crash: 시스템 고장

21. Benefits of database Integrity Security
Data in the database is accurate
Security
Having the complete jurisdiction over the data by DBA
Ensure proper channels to access DB
Define security rules for sensitive data (read, write, modify)
※integrity: 무결성, jurisdiction: 관할권

22. Benefits of database Balancing conflicting requirements Standards
Ex) Internal storage method of data
For fast access for the most important applications : eg. Index structure
slower access for certain other applications : eg. sequential file structure
Standards
Representation of data
Aid to data interchange or migration between systems
※sequential file: 순차파일

23. Benefits of database Data independence
Separation of physical and logical aspect of database
DBA can change physical storage structure and access strategy without having to modify existing applications
※access-strategy: 액세스방법