Chapter 7. Databases Chapter In Introduction to Computer. Pptx

1
Introduction To Computer
Lecture # 18-19
Lecturer in Department of Computer Science & Software Engineering,
International Islamic University, Islamabad

Outlin
es
Chapter 7:
Databases
Introduction
Traditional File Processing System
 Limitations of Traditional File
Processing Systems
Database Management System
 Advantages of DBMS
Database Design Concepts
Database Design
 Conceptual Database Design
 Logical Database Design
 Physical Database Design
Types of Database
MS Access
Database Design in MS Access

Introduction
Introduction To Computer & ICT – by Dr. Rahman Ali & Asmat Ali 3
• A collection of logically related data organized to be accessed, managed and
updated easily.
• Small data collection or a large scale database.
• Used for various purposes including:
 Storing internal data
 Analyzing the market
 Analyzing users’ interest
 Discovering patterns in data and more.
• Information is organized in rows and columns
(forming tables).
• Indexed information:
 Easier search.
 Easier modification.
 Easy to add or remove data items.

Introduction
 Data
• Facts concerning objects and events.
• A salesperson’s data:
 Names
 Addresses
 Phone numbers
 Items
 Prices and more.
• Numeric data
• Textual data
• Graphic data (Pictures and videos)
• Qualitative data
• Quantitative data.

Introduction
 Information
• Structured / processed data.
• Meaningful in some context.
• Well organized data on the basis of which an organization can take some
decision and can discover useful patterns in it.
Data Information

Introduction
 Metadata
• Data about data.
• Describes the characteristics and context of data.
• The primary mechanism to provide the context for data.
• Examples:
 Data type
 Length
 Maximum/minimum values

Traditional File Processing System
• Spreadsheets, word processing applications.
• A group of files that store data of an organization.
• Manual/computer based filling systems.
• All the departments have to maintain their own sets of files.
 Limitations
• Duplicate data; complex and hard to manage.
• Separate sets of files for each department or organization.
• Limited data sharing.
• Hard to develop and maintain.
• Excessive program maintenance.
• Less security.

Database Management System
• A computer software for creating and maintaining databases.
• A systematic way to create, retrieve, update and manage data.
• An interface between the database and the user.
• DBMS manages three things:
 The data.
 Database Engine, used to access and modify the data.
 Database Schema i.e. the logical structure of the database.
 Advantages
• Data Sharing
 A centralized database, visible to every user and department.
• Concurrency
 Multiple users can work with the database to add, update and update data.

Database Management System
 Advantages (continued…)
• Data Integrity
 Consistent, accurate and trustworthy data.
• Data Quality
 Improved data quality by specifying integrity constraints i.e. rules that can’t be
violated by database administrators.
• No Redundancy
 Data is recorded in a centralized database accessible from everywhere.
• Backup and Recovery
 Backup and recovery mechanism recovers the database in case of accidental loss.
• Security and Privacy
 Limited access to end users.
 Data can be accessed and modified only by authorized person.
 Limited privileges for each user

Database Design Concepts
 Entity
• A person, place, object or event.
• Must be of some interest to the organization.
• E.g. a college database may contain Student,
Teacher, Admission and Courses etc.
• Represented by a Rectangle.
Entities
Product
Customer
Order
Sales
man
Exam
Building
Room
Course

 Attributes
• A property of an entity that is of interest to the organization.
• E.g. the Student entity may have an id, name, address, admission number etc.
• Represented by circles, or alternatively in form of a table.

 Relationships
• An association that represents interaction among in a database.
• For example, a student in a college may have many courses and a course can be
completed by several students.
• A relationship may be:
 One to one
 Many to one
 Many to many

 Entity Relationship Diagram
• A detailed logical representation of the data in an organization.
 Entities
 Relationships among entities
 Attributes of the entities and relationships.

 Relation
• A named, two dimensional table of data with:
 A set of named columns (representing attributes)
 Arbitrary number of unnamed rows (representing data values for a single entity)
• In its simplest form, a relation is denoted as:
 Student (ID, Name, Address, Phone_no, Major)
• Or

 Table
• A collection of data held in a structured format within
a database.
• Vertical columns, identified by names.
• Horizontal rows, holding data for a single entity.
• Similar to relation with some differences:
 Metadata associated, e.g. constraints
 May have duplicate values unlike relation.

 Record
• A complete set of information, relevant to a specific entity.
• Also called row; comprised of a single row in a table.
• Example:
 The information (values against each attribute) for a specific student.

 File
• A related collection of records.
• Example:
 A collection of the records of all the students enrolled in a course.
 Field
• A data structure for a single piece of data.
• Example:
 Customer_ID, Name, Address, Phone_no are some of the fields in the table
Customer in an organization’s database.
• Fields are organized into records.

Database Design
 Conceptual Database Design
• First step of database design.
• Entities and their relationships are recognized by studying the organization.
• Output:
 Entity relationship model, comprised of entities and their relationships

Database Design
 Logical Database Design
• An extended version of the conceptual design:
 Entities, their attributes and the relationships.
 Primary keys (that uniquely define entities of an entity type).
 Foreign keys (used to relate two tables).
 Redundancy and other anomalies removed by Normalization.

Database Design
 Physical Database Design
• The logical database design is converted into a detailed design.
• Data types and lengths etc. of the attributes.
• The output is a design ready to be implemented.

Types of Database
 Flat File Database
• Files with no structured relationships among the records.
• Data is stored in a single table.
• Useful for storing small amount of records.
• Example: Spreadsheets.
 Document Oriented Database
• Data is stored in form of text records rather than tables.
• Useful for document based application.
 Embedded Database
• Runs within an application rather than a separate database application.
• Integrated with program that needs to store data.
• Hidden from the user, requiring little or no maintenance.

Types of Database
 Distributed Database
• A set of interconnected databases located at different locations.
• Logically a single database.
• Data is accessed and modified with the help of a network.

Types of Database
 Centralized Database
• Located and maintained on a single location.
• Accessible from different locations via a network.
 Knowledge Base
• Stores complex information used by computer systems.
• Structured or unstructured data.
• Examples:
 Expert system, which uses knowledge base containing facts about a specific field.
 Hypertext Database
• Used to organize large, dissimilar information.
• No regular structure, different from commonly used databases.
• Example:
 Databases for maintaining encyclopedias.

Types of Database
 Operational Databases
• Store data related to the operations in an organization.
• Used to modify (add, update or delete) data in real time.
• Example:
 A database storing daily transactions data of an organization.
 Online Database
• Database made accessible form the internet.
• Hosted on websites, to be accessed using a web browser.
• May be free or may require subscription.

MS Access
• A DBMS, part of the MS Office suite.
• Lightweight and easy to use tool for designing database.
• Not suitable for designing large scale databases.
• Used to design and maintain small scale databases.
• Key features:
 Creating databases
 Creating tables
 Creating relations
 Inserting data into tables
 Data validation
 Creating forms
 Creating Queries
 Creating reports and more.

Database Design in MS Access
 Creating Database
• File  New  Blank desktop database.
• Choose a destination folder and click “Create”.

 Creating Tables
• Navigate to Create tab on the ribbon and click
Table.
• A table “Table 1” will be created. Right click on it
and click “Save”.
• Name the table, e.g. Student.

 Creating Tables (continued…)
• Each table is created with one field, the ID.
• Right click it and rename to something relevant to the table, e.g. Student_ID.
• ID field should be “Auto Number” and “Unique” as it is the primary key.
• This is done by selecting the field and navigating to the FIELDS tab on the
ribbon.

 Creating Tables (continued…)
• To add a new field, click on “Click to Add” and select a suitable datatype, e.g.
“Short Text” for the field Name.
• Create all the fields in the table the same way
and save the table.
• Right click on the table and select “Design View”
to view the table in design view.

 Inserting Data into Tables
• Switch to datasheet view and insert records.
• The ID will be generated automatically for each record being inserted.

 Data Validation
• To restrict the user not to enter invalid data.
• E.g. currency and price can’t be negative, a field can accept only letters etc.
• Achieved by the use of validation rules.
• Add validation rules to a table:
 Right click on the table and select
“Design View”.
 Highlight the field to which a
validation rule is to be added.
 Add the validation rule against
“Validation Rule” in the field
properties.

 Validation Rules
• Example, validation rule for email field:
Is Null OR ((Like "*?@?*.?*") AND (Not Like "*[ ,;]*"))
Where “Is Null” means the field can be empty.
• Commonly used validation rules:
To do….. Validation Rule
Accept letters only Is Null OR Not Like "*[!a-z]*"
Accept digits only Is Null OR Not Like "*[!0-9]*"
Accept digits and letters only Is Null OR Not Like "*[!((a-z) or (0-9))]*"
Accept a string of exactly 5 characters Is Null OR Like "?????"
Accept a value of exactly 4 digits Is Null OR Like "####"
Accept positive numbers only Is Null OR >=0
Accept date that is not future date Is Null OR <= Date()
Accept only “Male” and “Female” Is Null OR "Male" OR "Female"

 Creating Query
• To manipulate data in the database, e.g. to update a field or delete a record.
• Example: Update student name in the first record.
 Create  Query Design
 Select the table (Students) and click Add.
 Next, click Update in Design tab

 Creating Query (continued…)
 Double click the field (Name) to be updated.
 Enter the new value in the Update To box.
 Also enter the old value in the Criteria box.
 Finally click Run in the Design tab to run the
query.

 Creating Forms
• An object used to create user interface for the database.
• Used to access and view data from one or more tables in a database.
• Procedure:
 Create  Form Wizard
 Select a table from the
dropdown list and double click
the fields which are to be added
to the form.

 Creating Forms (continued…)
 On the next screen, select a layout for the form.
 Give the query a name before finishing.
 In Form View, the output would be something like this.

 Creating Reports
• An object used to display data from the database.
• Pick data from one or more tables using a query and then create a report.
• Example:
 A report containing names, addresses and phone number of students.
 Create a query that selects
names, addresses and
phone number of all the
students in the table.
 Select the query and click
on Create  Report

 Creating Reports (continued…)
 The report opens in Layout mode where its layout can be changed.
 Switch to report view and you will see an output like this.

 Importing Tables to Database
• Import wizard is used to import tables etc.
from a .mdb or .accdb database.
• EXTERNAL DATA  Access
• Locate the existing database file in the wizard.
• Select “Import tables, queries, forms, reports, macros and modules”.

 Importing Tables to Database (continued…)
• Select the tables, queries and forms etc. that are to be imported into the
database.
• Click OK to finish import. The selected items should appear in your database.

 Linking Tables with Database
• To have one or more tables in multiple databases.
• The tables are stored in a single database and are linked to as many
databases as needed.
• Eliminates the need to enter or update the same data multiple times.
• Procedure:
 Similar to importing tables to database.
 Repeat the process, selecting “Link to data
sources by creating a linked table”.
 The linked tables appear in the database with
a star.

References
 Ali, R. & Ali, A. (2018). Chapter 7: Databases. Introduction to Computer
and ICT – 1st Edition (pp. 117-139). Muhalla Jangi, Qissa Khawani,
Peshawar, Pakistan: Al-ilum Publications.

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