1. File Processing and Data
Management Concepts
Chapter 12

2. Define the basic terms used in database technology.
Learning Objective 1
Define the basic terms used
in database technology.

3. Introductory Terminology
Field
These are used
interchangeably
to denote the
smallest block
of data that will
be stored and
retrieved.
Data items
Attribute
Elements

4. Introductory Terminology
A field may be a single character or number, or it
may be composed of many characters or numbers.
Customer name
Employee social security number
Purchase order number
Customer account number

5. Introductory Terminology
Logical grouping of fields are called records.
An employee
A customer
A vendor
An invoice

6. Data Occurrences Ocurrences = Instances
A record occurrence is a specific
set of data values for the record.

7. Data Occurrences For the record EMPLOYEE (NAME, NUMBER, AGE)
we might have the occurrence
EMPLOYEE (Brown, , 33)

8. Fixed- and Variable-Length Records
In a fixed-length record, both the number
of fields and the length (character
size) of each field are fixed.
In variable-length records, the width of the
field can be adjusted to each data occurrence.
A trailer record is an extension of a master record.

9. Several Suppliers and Warehouses Example
PART_NO
PNAME
TYPE
COST
PVEND – the name of the vendor or supplier
WARHSE – where the part is stored
LOC – the last two digits of the zip code

10. One Storage Location Example
PART (PART_NO, PNAME, TYPE, COST,
PVEND #1, WARHSE #1, LOC#1,
PVEND #2, WARHSE #2, LOC#2)

11. Repeated Groups Repeated groups are related groups of fields
that repeat themselves in variable-length records.
Segments
Groups
Nodes
PART, SUPPLIER, and LOCATION
can be written as follows:
PART (PART_NO, PNAME, TYPE, COST)

12. Tree Diagram for PART, SUPPLIER and LOCATION

13. Record Key and File Sequence
A key or record key is a data item or
combination of data items that uniquely
identifies a particular record in a file.
Primary sort key
Secondary sort key
Tertiary sort keys
Relative random order

14. Identify the three levels of database architecture.
Learning Objective 2
Identify the three levels of
database architecture.

15. Database Management Systems and Their Architecture
Database contents
Uses of database
Desired reports
Information to be reviewed
Conceptual
level

16. Database Management Systems and Their Architecture
Logical data structures:
Tree (hierarchical)
Network
Relational
Logical
level

17. Database Management Systems and Their Architecture
Access methods:
Sequential
Indexed-sequential
Direct
Physical
level

18. Conceptual Architecture
The Entity-Relationship (E-R) data model
is a conceptual model for depicting the
relationships between segments in a database.
"Entity" instead of segment
Attribute refers to individual fields or data items.

19. Conceptual Architecture
The object-oriented modeling technique
(OMT) views the components of the
system being modeled as object classes.
Object class corresponds to a segment.
Object corresponds to a particular instance.
Inheritance

20. Example of Object-Oriented Data Modeling Technique
PLANT_EQUIPMENT
ACCOUNT_NO
COST
DEPRECIATION
HEAVY_EQUIPMENT
MAINTENANCE_FREQ
DATE_PURCHASED
HAND_TOOLS
USAGE

21. Compare and contrast the different logical models of databases.
Learning Objective 3
Compare and contrast
the different logical
models of databases.

22. Logical Data Structures
The relationships that exist between
the segments in the database are
determined by the logical data structure,
also called the schema or database model.

23. Logical Data Structures
What are the three major models
of logical data structure?
1. Tree or hierarchical structures
2. Network structures
3. Relational models

24. Logical Data Structures
Tree (hierarchical) model
(4 levels and 13 nodes) A B C D E F G H I J K L M

25. Logical Data Structures
Network model
(3 levels and 11 nodes) A B C D E F G H I J K

26. Logical Data Structures
Both trees and networks are implemented
with imbedded pointer fields.

27. Implementing Tree and Network Structures
In a list organization, each record
contains one or more pointers
(fields) indicating the address
of the next logical record
with the same attribute(s).
A ring structure differs from a list
in that the last record in the ring
list points back to the first record.

28. Implementing Tree and Network Structures
What is a multiple ring structure?
In this type of structure several rings
pass through individual records.

29. List Structure Location of first record Attribute Records Index 1 2 3 4 5
Red
Blue
Index
Pointer field
to next record
End of list
indicator

30. Ring Structure Location of first record Attribute Index Pointer field2 Va 3 Ky
Pointer field
to next record
Pointer field
to first record
Records 1 2 4 3 4 5 5 2

31. Relational Data Structures
What is the relational model?
It is a logical data structure that
views the database as a collection
of two-dimensional tables.
There are no complicated pointers or lists.

32. Relational Data Structures
Relational algebra
Normal forms
Normalization

33. Relational Data Structures
What are the three normal forms?
First normal form
Second normal form
Third normal form

34. Explain the different methods
Learning Objective 4
Explain the different methods
of accessing files.

35. Database Architecture: The Physical Level
Sequentially accessed files
Indexed files
Directly accessed files

36. Sequentially Accessed Files
In a sequential access file, records
can only be accessed in
their predefined sequence.
Sequential file organization is useful
when batch processing is required.

37. Indexed Files An index file is one where an attribute has
been extracted from the records and used
to build a new file whose purpose is to
provide an index to the original file.
One important type of indexed
file is an indexed-sequential file.

38. Indexed Files An indexed-sequential file is a sequential file
that is stored on a DASD and is both indexed
and physically sorted on the same field.
These files are frequently
referred to as ISAM files.

39. Indexed Files An ISAM file structurally consists
of three distinct areas:
The index
The prime area
The overflow area
How would a computer locate a file
record whose key is 1002?

40. Structure of an ISAM File
Highest key
Track index address
Master Index
1500
0300
Track address
Track Index
Track
address
1005
0301
0300
Highest key
on track
Prime Area
Key
Data
Track
address
1002
Record found
0301

41. Directly Accessed Files
Direct-access files allow individual
records to be almost instantly retrieved
without the use of an index.
Each record is assigned to a storage
location that bears some relationship
to the record’s key values.
Most direct-access file systems convert
a key to a storage location address.

42. Use of a Direct-Access File
Processing logic flowchart:
Data
records
Randomizing
computation
(÷ 7)
Add
remainder to
displacement
address (10)
File
storage
area

43. Use of a Direct-Access File
File loading illustration:
Remainder
after
division
by seven
Displacement
factor
(initial address
of file area)
Key
Record
storage
address 1 3 4 10 15 17 11 22 2 13 14 + = 
Overflow

44. Use of a Direct-Access File
Storage area contents after loading:
Range of
randomizing
computation
Storage
allocated for
overflow
records …
Record 1 KEY 15*
Record 2 KEY 17
Record 3 KEY 11
Record 4 KEY 22
Contents
Address 10 11 12 13 14 15 16 17 18
Overflow
indicator

45. Economic Relations between File Organization Techniques
The basic economics of file processing are
largely determined by the activity ratio.
What is the activity ratio?
It is the number of accessed records divided
by the number of records in the file.
The second economic consideration
concerns response time.

46. Economic Relations between File Organization Techniques
What is response time?
It is the length of time the user must wait
for the system to complete an operation.
Response time is affected
by the physical access time.
Another factor that can affect response time is how
data records are physically distributed on the disk.

47. Learning Objectives 5 and 6
Explain the benefits
of database
management systems.
Describe the considerations
that are appropriate to the
design of computer-based
files and databases.

48. Database Management Systems and Databases in Practice
Database Management Systems (DBMS)
are computer programs that enable a user to
create and update files, to select and retrieve
data, and to generate various outputs and reports.
All DBMS contain three common attributes
for managing and organizing data.

49. Database Management Systems and Databases in Practice
What are these attributes?
Data description language (DDL)
Data manipulation language (DML)
Data query language (DQL)

50. Why Database Management Systems are Needed
DBMS integrate, standardize, and provide
security for various accounting applications.
In the absence of integration, each type of
accounting application such as sales, payroll,
and receivables will maintain separate,
independent data files and computer programs.

51. Database Management Concepts
Independent files:
Application One X Y B A
Application Two X Y C D

52. Database Management ConceptsX Y A B C D X Y A B
Database
dictionary and
access codes
Database
system
Logical file 1
Application one
Data
manipulation
routines D A Y X X Y C D
Logical file 3
Security screened inquiry file
Logical file 2
Application two

53. Database Documentation and Administration
Database dictionaries are used both alone
and with DBMS to centralize, document,
control, and coordinate the use of data
within an organization.
The data dictionary is simply another file,
sort of file of files, whose record occurrences
consist of data item descriptions.

54. Data Dictionary Format
Items in a data dictionary occurrence:
Specifications
Name
Definition
Aliases
Characteristics
Size
Range of values
Encoding
Editing data
Utilization
Owner
Where used
Security code
Last update

55. End of Chapter 12