Database

A Database is a repository for collection of related data or facts. A database contains a collection of related items or facts arranged in a specific structure. The most obvious example of a non computerized database is a telephone directory. Telephone companies now use an electronic database program to produce their printed phone books. Sometimes, we see a specialized phone book that is sorted not only by last name, but by other items such as phone number or street address. These books are easy to produce because the telephone company's electronic database can sort and organize the data in many different ways. Database programs can also sort lists of data, arranging them in alphabetical, numeric, or chronological order and can search or query data with different conditions.

Features of Database

The data in a database should have following features

Shared : Data in a database is sharing among different user and application.
Validity : Data should be correct with respect.
Security : Data should be protected from unauthorized user access.
Non-redundancy : No two data items in a database should represent the same real word entity.
Consistency : Data in a database should be same for all users.

Comments

Introduce Linux, UNIX and Linux distribution.

. Linux Linux is an open source operating system. The term Linux is actually referred to mean a kernel of Unix like operating system developed by a Finish software architect Linus Torvald. The name Linux is derived from Linus' Unix. Linux was originated from the inspiration of a small Unix like operating system MINIX by A.S Tanenbum. Linux is a complete multiuser, multiprocessing, secure and stable operating system which is also considered as UNIX clone. However no code from the proprietary from AT and T is included in Unix. It has flavor of Unix but is not Unix. UNIX UNIX is a layered operating system. The innermost layer is the hardware that provides the service for the OS. The operating system, referred to in UNIX as the kernel, interacts directly with the hardware and provides the services to the user program. These user programs don't need to know anything about the hardware. They just need to know how to interact with the kernel and it's up to the kernel to provide ...

Introduction of Computer

. A computer is an electronic device. It take input and store the data in memory and performing the function to produce accurate result in output device. It is used to type document, send email, play game, browse the web and entertainment. Characteristics of computer 1 . High speed Computer is very fast device. It is capable of performing calculation of very large amount of data. The computer has unit of speed in microsecond, nanosecond and even in picosecond. The computer is capable of performing millions of tasks per second. 2. Accuracy The computer produces highly accurate and reliable result. It does not make any kind of mistake in calculating. The calculation are 100% error free. The computers perform accurate 'n' number of times. 3. Storage capability A computer has much more storage capability. It can store large amount of data. It can store any type of data such as image, video, text document, audio and many more. 4. Diligence Diligence ...

Open System Interconnect (OSI) Reference Model

. Open system interconnection (OSI) Model explains how packet travels through various layers to other devices on a network, even if the sender and destination have different types of network media. Layer 1(Physical layer): Function To activate, maintain, deactivate the physical connection. To define voltage and data rates needed for transmission. To convert the digital bits into electrical signals. To decide weather the transmission the transmission is simplex, half or full duplex. Physical layer doesn’t perform the detection and correction of errors. Layer 2 (Datalink layer): Framing (stream of bits into manageable data units): The datalink layer divides the stream of bits received from the network layer into frame manageable data units called frames. Physical addressing (MAC Address): Data link layer adds a header to header to the frame to define the sender and receiver of the frame. Flow Control (mechanism for overwhel...

Computer Engineering

Search This Blog