Databse management system

Information System Architecture:
Data Structure and DBMS
Presented By
Engr. Md. Fazlul Kader
Assistant Professor, Dept. of APECE
University of Chittagong, Bangladesh

Contents
Some useful data structure
Data analysis
Data validation
Validation methods
Database Management System
Engr. Md Fazlul Kader

Data Structure
 Data may be organized in many different ways;
 The logical or mathematical model of a particular organization of data is
called a data structure.
 Useful Data Structures:
 A linear data structure is one in which, while traversing sequentially, we can
reach only one element directly from another. Eg- Linked List, Array.
 Array: a series of objects all of which are the same size and type. Each object in
an array is called an array element.
 Linked List:
 a linked list is a data structure consisting of a group of nodes which together
represent a sequence.
 A linked list is a finite sequence of nodes each of which contains a pointer field
pointing to the next node.
Let A is an array, then the elements of A are
denoted by subscript notation: A[0],A[1],A[2]….

Data Structure
 Record
 A record is a collection of related data items, each of
which is called a field or attribute
A Record
An Attribute

Record vs Linear Array
 A record may be a collection of non-homogeneous data
i.e. the data items in a record may have different data
types.
 The items in a record are indexed by attribute name, so
there may not be a natural ordering of its elements.

Data Analysis
 Data analysis is a process in which raw data is ordered
and organized so that useful information can be extracted
from it.
 The process of organizing and thinking about data is key
to understanding what the data does and does not
contain.
 Charts, graphs, and textual writeups of data are all forms
of data analysis.

Data validation
 Data validation is the process of ensuring that
a program operates on clean, correct and
useful data.
 It uses routines, often called "validation rules"
or "check routines", that check for correctness,
meaningfulness, and security of data that are
input to the system.

Validation methods
1. Allowed character checks:
 Checks that ascertain that only expected characters are present in a field.
 For example a numeric field may only allow the digits 0-9, the decimal point and
perhaps a minus sign or commas
2. Consistency checks
 Checks fields to ensure data in these fields corresponds, e.g., If Title = "Mr.", then
Gender = "M“
3.Control totals
 This is a total done on one or more numeric fields which appears in every record.
 This is a meaningful total, e g., add the total payment for a number of Customers.
4.Data type checks
 Checks the data type of the input
 Give an error message if the input data does not match with the chosen data type,
 e.g., In an input box accepting numeric data,if the letter 'O' was typed instead of the
number zero, an error message would appear..

Validation methods
5.File existence check
 Checks that a file with a specified name exists. This check is essential
for programs that use file handling.
6.Format or picture check
 Checks that the data is in a specified format (template), e.g., dates
have to be in the format DD/MM/YYYY.
7.Limit check
 Unlike range checks, data are checked for one limit only, upper OR
lower, e.g., data should not be greater than 2 (<=2).
8.Logic check
 Checks that an input does not yield a logical error, e.g., an input value
should not be 0 when there will be a number that divides it somewhere
in a program

Validation methods
9.Presence check/Missing Data Test
 Checks that important data are actually present and have
not been missed out, e.g., customers may be required to
have their telephone numbers listed.
10.Range check
 Checks that the data lie within a specified range of values,
e.g., the month of a person's date of birth should lie
between 1 and 12.
11.Uniqueness check
 Checks that each value is unique. This can be applied to
several fields (i.e. Address, First Name, Last Name).

Database Management System
 A database management system (DBMS) is the software
that allows a computer to perform database functions of
storing, retrieving, adding, deleting and modifying data.
 A database can be limited to a single desktop computer or
can be stored in large server machines
 Examples:
 Microsoft Access, MySQL, Microsoft SQL Server, Oracle

Features
 Features commonly offered by database management systems
include:
1. Query ability:
 Querying is the process of requesting attribute information from various
perspectives and combinations of factors.
 Example: "How many 2-door cars in Texas are green?"
2. Backup and replication
 Copies of attributes need to be made regularly in case primary disks or other
equipment fails.
 A periodic copy of attributes may also be created for a distant organization that
cannot readily access the original.
 DBMS usually provide utilities to facilitate the process of extracting and
disseminating attribute sets.
 When data is replicated between database servers, so that the information
remains consistent throughout the database system and users cannot tell or even
know which server in the DBMS they are using, the system is said to exhibit
replication transparency.

Features
3.Rule enforcement
 Applying rules to attributes so that the attributes are clean and
reliable.
 For example, we may have a rule that says each car can have only
one engine associated with it (identified by Engine Number). If
somebody tries to associate a second engine with a given car, we
want the DBMS to deny such a request and display an error message.
4.Security
 Limiting who can see or change which attributes or groups of
attributes.
 This may be managed
 directly by individual, or
 by the assignment of individuals and privileges to groups, or
 through the assignment of individuals and groups to roles which are then
granted entitlements.

Features
5.Computation
 There are common computations requested on attributes such as counting,
summing, averaging, sorting, grouping, cross-referencing, etc.
 Rather than have each computer application implement these from scratch,
they can rely on the DBMS to supply such calculations.
6.Change and access logging
 Often one wants to know who accessed what attributes, what was changed,
and when it was changed.
 Logging services allow this by keeping a record of access occurrences and
changes.
7. Automated optimization
 If there are frequently occurring usage patterns or requests, some DBMS can
adjust themselves to improve the speed of those interactions.
 In some cases the DBMS will merely provide tools to monitor performance,
allowing a human expert to make the necessary adjustments after reviewing
the statistics collected.

Advantages
 Reduced Data Redundancy
 Reduced Updating errors and increased consistency
 Greater data integrity and independence from
application programs
 Improved data access to users through use of host and
query language
 Improved data security
 Reduced data entry, storage and retrieval costs
 Facilitated development of new application program

Disadvantages
 Database systems are complex, difficult and time-
consuming to design
 Substantial hardware and software starting costs
 Damage to database affects virtually all application
programs
 Extensive conversion costs in moving form a fie-
based system to a database system
 Initial training required for all programmers and users

THANK YOU

Databse management system

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