6. What is Database?
Database
can be define as
According to Shelly & Varmaat
an integrated collection of related data or collection of data organized in a manner that allows
According to Petersen
a collection of data, manage and organized by a database management system.
8. Function of Database
Storing and Retrieving Data
The database sees the physical view of the data
How the data are compressed and formatted, which data are stored
near each other, and which indexes are created to simplify and speed
finding on the storage medium.
The database presents a logical view to the user and programmer
Organizes presents data elements in ways that managers and other
users find helpful .
9. This particular function is used for the storage of data and any related
data entry forms or screen definitions or report definitions structures
that can also handle video and picture formats. Users do not need to
know how data is stored or manipulated.
it enables multiple users to access the database simultaneously
without affecting the integrity of the database.
Multiuser Access Control
Function of Database
Data Storage Management
10. The concept that a transaction cannot be split into smaller parts
If systems fails in midst of transaction, system is restored as if the entire
transaction completed or no part of it completed .
Even Databases cannot be backed up like files because they are
too large and in constant use..
Backup techniques include
Operating in parallel on two storage devices
Use of temporary database during backup.
Providing Backup and Recovery
Function of Database
Providing Transaction Atomicity
11. The concept that a transaction cannot be split into smaller parts
If systems fails in midst of transaction, system is restored as if the entire
transaction completed or no part of it completed.
Most DBMSs can limit who has access to specific data .
DBMS can create limited views of data so that users can see only what
they are authorized to see.
Providing Authorization and Security Services
Function of Database
Providing Transaction Atomicity
14. RELATIONAL DATABASE
A relational database is a database that has a collection
of tables of data items.
Data in a single table represents a relations.
Tables consist of rows and columns.
The columns constitute the attributes.
The rows constitute tuples.
15. DOCUMENT ORIENTED DATABASE
A computer program designed for storing, retrieving and managing
document oriented information.
Documents inside a document-oriented database are similar to
records or rows in relational databases.
Do not store data in tables with uniform sized fields for each record.
16. EMBEDDED DATABASE
The databases consist of data developed by individual end
users.
Examples of these are collection of documents, spreadsheets,
presentations and other files.
17. GRAPH DATABASE
A graph database is a database that uses graph structures with nodes,
edges, and properties to represent and store data.
A graph database is any storage system that provides index-free
adjacency.
This means that every element contains a direct pointer to its adjacent
elements.
18. HYPERTEXT DATABASE
Hypertext databases are particularly useful for organizing large amount of
disparate information.
Hypertext is text displayed on a computer display or other electronic
devices with references to other text which the reader can immediately
access.
Pages often written in HTML.
19. OPERATIONAL DATABASE
An operational database contains data about the things that go on
inside an organization or enterprise.
Example: data on customer complaints, employee information, etc.
20. DISTRIBUTED DATABASE
It is a database in which portions of the database are stored on multiple
computers within a network.
The DDBMS synchronizes all the data periodically.
Updates and deletes performed on the data at one location will be
automatically reflected in the data stored elsewhere.
22. Users of Database
BANKING
a) For customer, informaion, account,
b) and loans, and transaction.
Airline
For reservation and schedule
information. Airline were among the
first to use database in a
geographically distributed manner.
Universities
For students information, course
registration, and grades.
Credits card
transactionFor purchases on credits cards and
generation of monthly statements
Sales
For customer, product, and purchase
information
Human resources
For information about employees,
salaries , payroll taxes and benefits,
and for generation of paychecks.