Database Systems

1
Database Systems

• ???
• hchgao_at_xidian.edu.cn

2
Major Content Grade

• Introduction
• The Relational Model
• SQL
• Transaction Management
• Database Design (E-R)
• Database Design (Normalization)
• ????
• ??(70)??(??/??/??) (30)

3
Books

• Book
• Abraham Silberschatz, Henry F. Korth,
  S.Sudarshan, Database System Concepts (5th ed.),
  The McGraw-Hill Companies, 2006
• Reference Books
• Thomas M. Connolly, et al. Database Systems A
  practical approach to Design, Implementation, and
  Management. 4th edition, Addison-Wesley, 2008
• ???,?? ??????? ???????
• (?4?)

4
Unit 1 Introduction

• Data Database
• DBMS
• Database System
• Database Applications
• Brief History of Data Management

5
Data Database

• How to management Information (Data)?

• data data are raw facts that describe people,
  objects, and events.

6
Data Database

• How to management Information(Data)?

• Database An integrated collection of related
  data constitutes a Database (DB).

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DBMS

• Database Management System (DBMS) Contains
  information about a particular enterprise
• Collection of interrelated data
• Set of programs to access the data
• An environment that is both convenient and
  efficient to use

8
DBMS

• What should A DBMS needed?

• Data can be shared
• Redundancy(??) can be reduced
• Inconsistency(????) can be avoided
• Transaction(??) support can be provided
• Integrity(???) can be maintained
• Security(???) can be enforced
• Conflicting(??) requirements can be balanced
• Standards can be enforced

DBMS is less complex than OS.
9
DBMS Architecture
??? ??? ???
??xxxxx ??xxx ??x
???? ???? 75
????? ????? 81

• ???(External Schema,??????????)
• ???????????????????????

• ??(Logical Schema, Schema,??????)
• ????????????????(?)???

Sno Sname Ssex Sage Sdept
Cno Cname Cpno Ccredit
Sno Cno Grade

• ???(Physical Schema,??????)
• ??????????????

10
DBMS Architecture

• ANSI/SPARC architecture

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Functions of DBMS

• 1) Data definition(Data Definition LanguageDDL)
• ??DDL???????????????????
• 2) Data manipulation(Data Manipulation
  LanguageDML)
• ????DML?????????????,??????????????
• 3) Database running management
• ??????????????,?DBMS???????????,?????????????
  ?????????????????????
• 4) Database establish and maintain
• ?????????????????????????????????????????????
  ?????DBMS???????????

12
Database System

• Database System A computerized record-keeping
  systems, composed by Data, Hardware, Software
  and People

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Components of Database System

• Data
• Anything that is of significance to the
  individual or organization concerned
• Two characters
• integrated - neednt include redundant
  information
• shared a record file should be shared by
  different user
• Multi-views
• Hardware
• Secondary storage volume
• I/O device, Device controller, I/O channel,
  etc
• Processor and Main memory

14
Components of Database System

• Software
• OS
• Unix,Linux, OS/2, Windows NT
• Database Management System
• Oracle, DB2, Sybase, MySQL, PostgreSQL,
• Others software
• utilities, application development tools,
  designs aid, report writer, transaction manager

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Components of Database System

• People
• End usersInteractive users.
• Casual users (????)facility with SQL
• Naive users (????) bank clerks
• Application programmers
• An application programmer, in the sense used with
  DBMS, writes the menu applications used by naive
  users.
• DBA (database administrator)
• A DBA is a computer professional responsible for
  the design and maintenance of the database.

16
???????????????

• Charles W. Bachman(??? ???) 1973
• ????????????????????IDS,????????????????????????
  ??????????,?DDL?DML?????
• Edgar F. Codd(??? ??) 1981
• ?1970?6??????A Relational Model of
• Data for Large Shared Data Banks??,??
• ?????????????????????
• ?,????????????????
• James Gray(??? ??) 1998
• ????????????????????,
• ????????????????????
• ??????????????,?????
• ????????????????

17
Unit 1 Introduction

• Data Database
• DBMS
• Database System
• Database Applications
• Brief History of Data Management

18
Database Applications

• Database contains information about a
  particular enterprise.
• Database Applications
• Banking all transactions
• Airlines reservations, schedules
• Universities registration, grades
• Sales customers, products, purchases
• Manufacturing production, inventory, orders,
  supply chain
• Human resources employee records, salaries, tax
  deductions
• Databases touch all aspects of our lives

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Database Applications Architecture

• Client/Server architecture

20
Database Applications Architecture

• Browser/Server architecture

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Brief History of Data Management

• In the early days(Before 1960s), database
  applications were built on top of FILE systems

22
Brief History of Data Management

• Drawbacks of using FILE SYSTEMS
• Data redundancy and inconsistency(????)
• Difficulty in accessing data
• Data isolation
• Integrity problems
• Atomicity of updates
• Concurrent access by multiple users
• Security problems
• Its impossible to programmers for even ONE
  solution!

23
Brief History of Data Management

• Management using DBMS

• Database systems offer solutions to all the
  above problems in using file systems !

24
History of Database System

• Hierarchical system (1960s)
• IBMs IMS
• data represent to user is the form of tree
  structure
• IMS provided the hierarchical data model, where
  different kinds of records relate to one another
  in a hierarchical form.
• data shared by several applications

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Example of Hierarchical system
??
???
R0101 ???????
R0102 ???????

R0301 ?????
R0302 ??????
R0303 ?????

D01 ???? ??II?
D02 ???? ??III?
D03 ??? ??I?

??
E0102 ??? ?
E0103 ??? ?

E0313 ?? ?
E0315 ??? ?

• ???????????!

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History of Database System

• Network System (1960s)
• Cullinet Software IDMS (CODASYL DBTG Report)
• The network data model, a generalization of the
  hierarchical model where a set of record in one
  layer might have two different containing
  hierarchies at the next layer up.
• data represent to user is graph structure
• operator similar to hierarchical system

Bachman
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Example of Network System
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History of Database System

• Relational system (1970s)
• data representation are table, operator generate
  new tables from old tables
• In a relational database, all information is
  represented in the form of named tables
  (relation) with labeled column (attribute)
• In the relational model, a column of a table must
  contain a single, unstructured value(first normal
  form rule)
• Products SQL server, Oracle, Sybase, DB2,
  Informix, Ingres, etc.

Codd
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Example of Relational System
enrollment (??)
students
sid lname fname class tel
1 Jones Allan 2 88201234
2 Smith John 3 88201233
3 Brown Harry 2 88202255
4 White Edward 3 88201688
sid cno major
1 101 No
1 108 Yes
2 105 No
3 101 Yes
3 108 No
4 102 No
4 105 No
courses
cno cname croom time
101 English I I-101 MW2
102 English II I-102 MW3
105 Math II-101 MW2
108 Chinese II-202 MW4
30
History of Database System

• Object-Relational system (1980s)
• In an object-relational database, information is
  still represented as in the relational model in
  the form of named tables with labeled columns
• but the column values are no longer restricted
  by the First Normal Form rule (can be STRUCT or
  SET datatype).

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Example of ORDBMS
students
Sid name name class tel enrollment enrollment
Sid lname fname class tel cno major
1 Jones Allan 2 88201234 101 No
108 Yes
2 Smith John 3 88201233 105 No
3 Brown Harry 2 88202255 101 Yes
108 No
4 White Edward 3 88201688 102 No
105 No
courses
cno cname croom time
101 English I I-101 MW2
102 English II I-102 MW3
105 Math II-101 MW2
108 Chinese II-202 MW4
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History of Database System

• 1990s
• Large decision support and data-mining
  applications
• Large multi-terabyte data warehouses
• Emergence of Web commerce
• 2000s
• XML and XQuery standards
• Automated database administration