USERS HAVE REQUIREMENTS FOR INFORMATION SYSTEM

1
ASPECTS OF FILE PROCESSING APPROACH

• USERS HAVE REQUIREMENTS FOR INFORMATION SYSTEM
• APPLICATIONS.
• USERS EITHER COMMISSION IS STAFF TO DEVELOP
• APPLICATION, OUTSOURCE IT, OR INCREASINGLY,
  DEVELOP
• IT THEMSELVES USING PC SOFTWARE.
• REGARDLESS OF WHO DOES IT, PROGRAMMING PROCESS IS
• ERROR-PRONE AND TIME-CONSUMING.
• EACH APPLICATION REQUIRES ITS OWN DATA IN ITS OWN
• FORMATS STORED IN ITS OWN FILES.

2
PROBLEMS WITH FILE PROCESSING ENVIRONMENT

• UNCONTROLLED REDUNDANCY
• - Data
• - Programs
• DATA INCONSISTENCY
• - Redundant data is difficult to keep in synch
• LIMITED SHARING OF DATA
• - File structure incompatibility (ex ISAM vs
  Direct Access)
• - System software incompatibility (ex Oracle vs
  M/S Access)
• INFLEXIBILITY OF AVAILABLE INFORMATION
• - Files tend to isolate information and restrict
  what can be retrieved
• POOR ENFORCEMENT OF STANDARDS

3
ELEMENTS OF DB APPROACH
(1) DATA AS A RESOURCE Data considered as a
resource in same way hardware/software/personnel
are considered as resources. (2) DATA
INDEPENDENCE Data format/structure independent
of particular application. User view of data
not tied to physical representation of
data. (3) DATABASE MANAGEMENT SYSTEM
(DBMS) DBMS is software which coordinates
data resources in the same way that an
operating system (OS) coordinates system
resources. (4) DATABASE MANAGEMENT The
management of hardware/software/ DBMS/data which
implements DB approach.
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DATABASE APPROACH
(1) Put data into common databases that can be
accessed and shared by multi- ple users.
DB1
DB2
DB3
Shared Data Resource
(2) Provide uniform storage, access,
and retrieval methodology for data. Ex High
level commands like STORE, UPDATE, RETRIEVE,
etc. (3) Provide generalized,
user-friendly interfaces so non-DP personnel
may interact directly with data
without programmers aid. Ex Query language
(SQL), DB application generators
(PowerBuilder, M/S Access)
5
BENEFITS OF DATABASE PROCESSING

• MINIMAL DATA REDUNDANCY
• Redundancy reduced (not eliminated) gt
  controlled redundancy.
• CONSISTENCY OF DATA
• Inconsistency managed via single, centralized
  source of data.
• INTEGRATION OF DATA
• Data are organized into single, logical structure
  with logical relationships
• between files
• Files can be joined, or integrated, where it
  makes sense files no longer in
• isolation.
• SHARING OF DATA
• All programs access same data using standardized
  commands
• DBMS supports multiple file structures
• Separate views of a database can be created for
  each user.
• DATA ACCESSIBILITY AND RESPONSIVENESS
• DBMS supports programmed and unanticipated
  queries and reports via SQL

6
CHALLENGES OF DATABASE APPROACH

• ORGANIZATIONAL CONFLICT
• Data ownership (Information is power.)
• Implementation of data standards.
• SPECIALIZED PERSONNEL
• Database personnel (database analysts, DBA, etc)
  require special skills and
• training.
• EXTENSIVE OVERHEAD OF MAINTAINING DATA INTEGRITY
• Security, privacy, concurrency, recovery and
  backups.
• DISTRIBUTED DATA MANAGEMENT
• Data management is centralized in its approach
  whereas distributed
• computing over networks is decentralized.

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COMPONENTS OF A DATABASE SYSTEM

• DATABASE
• - User Data
• - Metadata
• - Indexes
• - Application Metadata
• DATABASE MANAGEMENT SYSTEM (DBMS)
• - Design tools subsystem
• - Run-Time subsystem
• - DBMS Engine
• Data integrity
• Data dictionary
• APPLICATIONS
• - Forms
• - Queries
• - Reports
• - Menus
• - Application Programs

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KINDS OF DATA IN A DATABASE

• RECORD-BASED SOURCE DATA
• BITS gt BYTES gt FIELDS gt RECORDS gt FILES gt DB
• META-DATA
• DATA ABOUT DATA IN THE DATABASE. (E.g.,
  information about the
• data fields, their data types, and acceptable
  data values, etc.)
• DATA ABOUT APPLICATIONS (E.g., forms, queries,
  reports, etc.)
• OVERHEAD DATA
• INDEXES, KEYS, ETC.

9
FUNCTIONS OF A DBMS

• DATA DEFINITION
• Define and store database structure called the
  Schema
• (Metadata Overhead Data)
• Load source data into database
• Provide multiple views of data
• DATA MANIPULATION
• Provide variety of access methods to tables
• (ISAM, direct, B-tree, sequential, etc.)
• Query processing (SQL)
• Provide database interface commands in existing
  programming
• languages such as C, Java, C, Cobol.
• DATA INTEGRITY AND CONTROL
• Security
• Concurrent processing
• Backup and recovery

10
APPLICATION ENVIRONMENTS FOR DB PROCESSING

• LOOSELY-COUPLED vs TIGHTLY-COUPLED
• Access Basic vs Visual Basic or C
• DESIGN TOOLS
• Table creation tool
• Form creation tool
• Query creation tool
• Report creation tool
• Procedural language compiler
• RUN-TIME TOOLS
• Form processor
• Query processor
• Report writer