1. Database Management System
Lecture - 22
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2. Data Volume and Usage Analysis
Statistics about the size and usage of data plays critical role in data processing efficiency
Final step of logical DB design or first step in physical DB design
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3. Data Volume and Usage Analysis
Statistics collected during analysis phase from the users of the system
May not be accurate; give the tentative and relevant figures
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4. Data Volume and Usage Analysis
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5. © Virtual University of Pakistan
Composite Usage Map
PART
1000
MANUFAC-TURED PART
PURCHASED PART O
QUOTATION
SUPPLIER
2500
40 %
70 % 50
140
200 60 40 80 75
(50) 70
700
400
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Designing Fields
Field is smallest unit of application data; corresponds to a simple attribute
Involves different decisions about fields
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Choosing Data Type
Data type is defined as set of values along with the operations that can be performed on them
Precisely depends on the particular DBMS
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Choosing Data Types
Involves four objectives
Minimize storage space
Represent all possible values
Improve data integrity
Support all data manipulation
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Coding Techniques
Values of the attributes with small domains can be replaced by codes
Codes can be stored in lookup table or can be hard coded, example
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Coding Example
stId
stName
hobby
S1020
Sohail Dar
Reading
S1038
Shoaib Ali
Gardening
S1015
Tahira Ejaz
Movies
S1018
Arif Zia
STUDENT
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11. © Virtual University of Pakistan
Coding Example
STUDENT
HOBBY
stId
stName
hobby
S1020
Sohail Dar R
S1038
Shoaib Ali G
S1015
Tahira Ejaz M
S1018
Arif Zia
code
Hobby R
Reading G
Gardening M
Movies
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12. Controlling Data Integrity
Concerns the possible values that a field can assume
First such control is enforced by the data type
Some others are…
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13. Controlling Data Integrity
Default value
Range control
Null values
Referential integrity
Handling missing data
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14. Database Management System
Lecture - 22
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