Introduction to database & sql

WELCOME TO OUR PRESENTATION
INTRODUCTION TO DATABASE &
SQL
1

What is a Database?
2
 Database is a collection of related data, that
contains information relevant to an
enterprise.
 For example:
1. University database
2. Employee database
3. Student database
4. Airlines database
etc…..

PROPERTIES OF A
DATABASE3
 A database represents some aspect of the real
world, sometimes called the miniworld or the
universe of discourse (UoD).
 A database is a logically coherent collection of
data with some inherent meaning.
 A database is designed, built and populated
with data for a specific purpose.

What is Database Management
System (DBMS)?4
 A database management system (DBMS) is a
collection of programs that enables users to create &
maintain a database. It facilitates the definition,
creation and manipulation of the database.
 Definition – it holds only structure of database, not
the data. It involves specifying the data types,
structures & constraints for the data to be stored in the
database.
 Creation –it is the inputting of actual data in the
database. It involves storing the data itself on some
storage medium that is controlled by the DBMS.
 Manipulation-it includes functions such as updation,
insertion, deletion, retrieval of specific data and
generating reports from the data.

A SIMPLIFIED DATABASE
SYSTEM ENVIRONMENT55

Typical DBMS Functionality
6
 Define a database : in terms of data types,
structures and constraints
 Construct or Load the Database on a
secondary storage medium
 Manipulating the database : querying,
generating reports, insertions, deletions and
modifications to its content
 Concurrent Processing and Sharing by a set of
users and programs – yet, keeping all data
valid and consistent

Typical DBMS Functionality
7
Other features:
 Protection or Security measures to prevent
unauthorized access
 “Active” processing to take internal actions on
data
 Presentation and Visualization of data

Database System
8
 The database and the DBMS together is
called the database system.
 Database systems are designed to manage
large bodies of information.
 It involves both defining structures for storage
of information & providing mechanisms for the
manipulation of information.
 Database system must ensure the safety of the
information stored.

Database System Applications
9
 Banking- for customer information, accounts & loans, and
banking transactions.
 Airlines-for reservations & schedule information.
 Universities-for student information, course registration and
grades.
 Credit card transactions-for purchases on credit cards &
generation of monthly statements.
 Telecommunication-for keeping records of calls made,
generating monthly bills, maintaining balances, information
about communication networks.
 Finance-for storing information about holdings, sales &
purchases of financial instruments such as stocks & bonds.
 Sales-for customer, product and purchase information.
 Manufacturing-for management of supply chain & for
tracking production of items in factories.
 Human resources-for information about employees, salaries,
payroll taxes and benefits

Functions of Database administrators
(DBA)10
 Coordinating & monitoring the database
 Authorizing access to the database
 For acquiring hardware & software resources
as needed by the user
 Concurrency control checking
 Security of the database
 Making backups & recovery
 Modification of the database structure & its
relation to the physical database

Advantages of DBMS
11
 Controlling Redundancy
 Restricting Unauthorized Access
 Providing Storage Structures for Efficient
Query Processing
 Providing Backup and Recovery
 Providing Multiple User Interfaces
 Representing Complex Relationship among
Data
 Enforcing Integrity Constraints
 Permitting Inferencing and Actions using Rules

Disadvantages of DBMS
12
 Cost of Hardware & Software
 Cost of Data Conversion
 Cost of Staff Training
 Appointing Technical Staff
 Database Damage

Different parts of a database
 Fields
 Records
 Queries
 Reports

Fields
 Database storage units
 Generic elements of content

Records
A simple table showing fields (columns) and records(rows):
And as part of an MS Access database table:

Queries
 Queries are the information retrieval
requests you make to the database
 Your queries are all about the
information you are trying to gather

Reports
 If the query is a question...
...then the report is its answer
 Reports can be tailored to the needs of
the data-user, making the information they
extract much more useful

SQL is used for:
 Data Manipulation
 Data Definition
 Data Administration
 All are expressed as an SQL statement or
command.
19

Using SQL20
To begin, you must first CREATE a database using
the following SQL statement:
CREATE DATABASE database_name
Depending on the version of SQL being used
the following statement is needed to begin
using the database:
USE database_name

Using SQL
 To create a table in the current database,
use the CREATE TABLE keyword
21
CREATE TABLE authors
(auth_id int(9) not null,
auth_name char(40) not null)
auth_id auth_name
(9 digit int) (40 char string)

Table Design22
Rows
describe the
Occurrence of
an EntityName Address
Jane Doe 123 Main Street
John Smith 456 Second Street
Mary Poe 789 Third Ave
Columns describe one
characteristic of the entity

Using SQL
 To insert data in the current table, use the
keyword INSERT INTO
23
auth_id auth_name
Then issue the statement
SELECT * FROM authors
INSERT INTO authors
values(‘000000001’, ‘John Smith’)
000000001 John Smith

Data Retrieval (Queries)
 Queries search the database, fetch info,
and display it. This is done using the
keyword
24
SELECT * FROM publishers
pub_id pub_name address state
0736 New Age Books 1 1st Street MA
0987 Binnet & Hardley 2 2nd Street DC
1120 Algodata Infosys 3 3rd Street CA
The
*Operator asks for every column in
the table.

Data Input
 Putting data into a table is accomplished
using the keyword
25
Table is updated with new information
INSERT INTO publishers
VALUES (‘0010’, ‘pragmatics’, ‘4 4th Ln’, ‘chicago’, ‘il’)
0010 Pragmatics 4 4th Ln IL

Data Retrieval (Queries)
 Queries can be more specific with a few
more lines
26
Only publishers in CA are displayed
SELECT *
from publishers
where state = ‘CA’

Using SQL27
SELECT auth_name, auth_city
FROM publishers
auth_id auth_name auth_city auth_state
123456789 Jane Doe Dearborn MI
000000001 John Smith Taylor MI
auth_name auth_city
Jane Doe Dearborn
John Smith Taylor
If you only want to display the author’s name and city from the following
table:

Using SQL28
DELETE from authors
WHERE auth_name=‘John Smith’
To delete data from a table, use the DELETE statement:

Using SQL29
UPDATE authors
SET auth_name=‘hello’
To Update information in a database use the UPDATE keyword
Hello
Hello
Sets all auth_name fields to hello

Using SQL30
ALTER TABLE authors
ADD birth_date datetime null
To change a table in a database use ALTER TABLE. ADD adds a
characteristic.
ADD puts a new column in the table called birth_date
birth_date
.
.
Type Initializer

Using SQL31
ALTER TABLE authors
DROP birth_date
To delete a column or row, use the keyword DROP
DROP removed the birth_date characteristic from the table
auth_state
.
.

Using SQL32
DROP DATABASE authors
The DROP statement is also used to delete an entire database.
DROP removed the database and returned the memory to system

Introduction to database & sql

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