Transcript Data Modeling

Bayu Adhi Tama, ST., MTI.
Data Modeling
Thanks to Poniah, Elamasri, and Silberkatz
Review
LOGO
 DDL is usually used by database administrator (DBA) to
retrieve or to update data in a DBMS. [T/F]
 In a “two-tier architecture”, in order to increase
transaction processing, an application Server is used
beside a database server. [T/F]
 If the database system is not able to handle the complexity
of data because of modeling limitations, it’s enough when
no DBMS will use. [T/F]
LOGO
 A model serves two primary purposes:
 As a true representation of some aspects of the real world, a model
enables clearer communication about those aspects of the real world.
 A model serves as a blueprint to shape and construct the proposed
structures in the real world.
 Data modeling is an integral part of the process of designing and
developing a data system.
 A data model is a device that : [Poniah]
 helps the users or stakeholders understand clearly the database system
that is being implemented based on the information requirements of an
organization, and
 enables the database practitioners to implement the database system
exactly conforming to the information requirements.
 Data models [Silberkatz]
 A collection of tools for describing : data, data relationships, data
semantics, and data constraints
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 Data model: communication tool and database blueprint.
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 Classification of Information Levels:
 Conceptual Level. The highest level consisting of general ideas about
the information content
 External Level. The data model represents the information requirements
for the entire set of user groups in the organization
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 Process creating data model:
 Identify business objects
 Identify relationships
 Add attributes
 Assign identifiers
 Incorporate business rules
 Validate the data model
 Significance of data model quality
 Data model completeness
 Data model correctness
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 Data models characteristic
 Involves users
 Covers the proper enterprise segments
 Uses Accepted Standard Rules and Conventions.
 Produces High-Quality Design.
 Data system development lifecycle (DDLC)
 Starting the process
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Data-Oriented Approach
Development Framework.
Initiation Report.
Planning
Feasibility study
 Requirements definition
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Study overall business operations
Observes business processes
Understand business units
Interview users
Determine information requirements
Identify data to be collected and stored
Establish data access pattern and estimate data volume
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 Design
 Implementation
History of Data Models
Network Model
Hierarchical Model
Relational Model
Object-oriented Data Models
Object-Relational Models
Slide 2- 9
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History of Data Models
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Network Model:
 The first network DBMS was implemented by
Honeywell in 1964-65 (IDS System).
 Adopted heavily due to the support by
CODASYL (Conference on Data Systems
Languages) (CODASYL - DBTG report of
1971).
 Later implemented in a large variety of
systems - IDMS (Cullinet - now Computer
Associates), DMS 1100 (Unisys), IMAGE
(H.P. (Hewlett-Packard)), VAX -DBMS (Digital
Equipment Corp., next COMPAQ, now H.P.).
Slide 2- 10
Example of Network Model Schema
Slide 2- 11
LOGO
Network Model: Basic Concepts
 Data are represented by collections of records.
 Records and their fields are represented as
record type
 Relationships among data are represented by
links
 restrictions on links depend on whether the
relationship is many-many, many-to-one, or one-toone.
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Network Model
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Advantages:
 Network Model is able to model complex
relationships and represents semantics of
add/delete on the relationships.
 Can handle most situations for modeling
using record types and relationship types.
 Language is navigational; uses constructs like
FIND, FIND member, FIND owner, FIND
NEXT within set, GET, etc.
• Programmers can do optimal navigation through
the database.
Slide 2- 13
Network Model
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Disadvantages:
 Navigational and procedural nature of
processing
 Database contains a complex array of
pointers that thread through a set of records.
• Little scope for automated “query optimization”
Slide 2- 14
History of Data Models
LOGO
Hierarchical Data Model:
 Initially implemented in a joint effort by IBM
and North American Rockwell around 1965.
Resulted in the IMS family of systems.
 IBM’s IMS product had (and still has) a very
large customer base worldwide
 Hierarchical model was formalized based on
the IMS system
 Other systems based on this model: System
2k (SAS inc.)
Slide 2- 15
Hierarchical Model
LOGO
 Advantages:
 Simple to construct and operate
 Corresponds to a number of natural hierarchically
organized domains, e.g., organization (“org”) chart
 Language is simple:
• Uses constructs like GET, GET UNIQUE, GET NEXT, GET
NEXT WITHIN PARENT, etc.
 Disadvantages:
 Navigational and procedural nature of processing
 Database is visualized as a linear arrangement of records
 Little scope for "query optimization"
Slide 2- 16
History of Data Models
LOGO
 Relational Model:
 Proposed in 1970 by E.F. Codd (IBM), first commercial
system in 1981-82.
 Now in several commercial products (e.g. DB2, ORACLE,
MS SQL Server, SYBASE, INFORMIX).
 Several free open source implementations, e.g. MySQL,
PostgreSQL
 Currently most dominant for developing database
applications.
 SQL relational standards: SQL-89 (SQL1), SQL-92
(SQL2), SQL-99, SQL3, …
Slide 2- 17
History of Data Models
LOGO
 Object-oriented Data Models:
 Several models have been proposed for implementing in a
database system.
 One set comprises models of persistent O-O Programming
Languages such as C++ (e.g., in OBJECTSTORE or
VERSANT), and Smalltalk (e.g., in GEMSTONE).
 Additionally, systems like O2, ORION (at MCC - then
ITASCA), IRIS (at H.P.- used in Open OODB).
 Object Database Standard: ODMG-93, ODMG-version 2.0,
ODMG-version 3.0.
Slide 2- 18
Object Oriented Data Model
LOGO
 An object corresponds to an entity
 The object-oriented paradigm is based on encapsulating
code and data related to an object into single unit.
 The object-oriented data model is a logical data model
 Object structure:
 A set of variables that contain the data for the object. The value
of each variable is itself an object.
 A set of messages to which the object responds; each message
may have zero, one, or more parameters.
 A set of methods, each of which is a body of code to implement
a message; a method returns a value as the response to the
message
History of Data Models
LOGO
Object-Relational Models:
 Most Recent Trend. Started with Informix
Universal Server.
 Relational systems incorporate concepts from
object databases leading to object-relational.
 Exemplified in the latest versions of Oracle10i, DB2, and SQL Server and other DBMSs.
 Standards included in SQL-99 and expected
to be enhanced in future SQL standards.
Slide 2- 20
Exercise
 Match the column entries
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