All things you Want to Know about SQL & Oracle

• What is SQL?
• SQL stands for structured query language and it is the standard language for dealing withRelational databases. SQL was originally developed at IBM in early 1970s or a prototype called system R.It was initially spelt and pronounced as ‘SEQUEL’ but now is popularly called SQL only. It has an ANSI as well as ISO standard.
•  Which is the different version of SQL?
• Sql got its first ANSI standard in 1986. After the next standardization was in 1989 and the one in 1992 became very popular. It was also called SQL2. The latest version is SQL3. Which is being implemented by oracle 8 onwards? It supports some object-oriented features.
• Which is the different version of Sql?
• SQL can be broadly classified as-
• Data definition language (DDL)
• Data manipulation Language (DML)
• Data control language (DCL)
• Transaction control
• Data retrieval (queries)
• Sometimes the DCL commands are also considered to be part of DDL commands
• What do you understand by DDL?
• The DDL commands stands for Data definition Language and it related to the structured of an object.
• E.g.: Create, Alter, drop, rename, truncate
• What do you understand by DML?
• The DML commands are those related to the content of the table. They deal with insertion, updating and deletion of rows in a table.
• E.g. insert, update, delete
• What do you understand by DCL?
•  The DCL commands are required to give or take back access rights on object.
• E.g. GRANT, REVOKE
• What is transaction control?
• These commands are used to handle the unit of work. A transaction executes either as a whole or none of its statements execute.
• What is data retrieval?
• The main purpose of data retrieval is to display data (raw, column) in the required format.It is mainly used for querying and reporting purpose.
• What is the difference between char and varchar2?
• The CHAR and VARCHAR2 both are used to store data.
• The CHAR type is used to store fixed-length character data. The default and minimum size is 1 and the maximum size is 2000 characters.
• The Char data types uses all the space assigned to it as per the size mentioned and hence has more storage efficiency because of which it processes data faster than VARCHAR2
• .What is the concept of DUAL table?
• DUAL is the work table of oracle, which has only one raw and column.
• The column name is DUMMY with data type CHAR (1). 
• When you want to perform some temporary calculation using only literals (no variables) then this table is of great use. The actual dummy column is irrelevant.
• You can do all your temporary work on this table.
• What is the difference between the Where clause and the HAVING clause?
• The where clause is used to restrict rows. 
• It checks for the condition for each and every row of the table. The having clause is used to restrict groups.
• It is used immediately after GROUP BY clause and it checks for the conditions considering each group as a whole. 
• In syntax as well as during execution the WHERE clause is always evaluated before the HAVING clause.

Need of computer network

·         Resource sharing

·         High reliability

·         Saving money

·         Scalability

Advantages of computer network

·         Access to remote information

·         Person-to-person communication

·         Interactive entertainment

·         Program and file sharing

·         Network and resource sharing

·         Database sharing

·         Economical expansion

·         Ability to use network software

·         Creation of workgroup

·         Centralized management

·         Security

·         Access to more than one operation system

·         Manufacturing

new computer definations

• E-commerce hosting:E-commerce hosting is a business in which a company provides other companies whatever they need to sell their products and services on the World Wide Web.
• EDFA: An erbium amplifier, also called optical amplifier or an erbium-doped fiber amplifier or simply EDFA, is an optical or IR repeater that amplifies a modulated laser beam directly, without opto-electronic and electro-optical conversion.
• Ubuntu: Ubuntu is an open source Debian-based Linux distribution. Sponsored by Canonical Ltd, Ubuntu is considered a good distribution for beginners. The operating system was intended primarily for personal computers (PCs) but it can also be used on servers.
• Ubiquitious computing: Ubiquitious computing is the trend towards increasingly ubiquitous, connected computing devices in the environment, a trend being brought about by a convergence of advanced electronic and particularly wireless technologies and the Internet.
• Ultra HDTV: Ultra HDTV, also referred to as full-HDTV, true HDTV and 1080p, is a television display technology that surpasses the video quality and sharpness of the original high-definition television ( HDTV ) technology, providing an image resolution of 1920 by 1080 pixels.
• XDMA: XDMA (Xing Distributed Media Architecture) is a network architecture for multicast streaming media transmissions. Streaming media enables live viewing of a transmission as compared to processes that require that files be completely transferred to the user's computer before their data can be viewed.
• Typo squatting: Typo squatting, also called URL hijacking, is a form of cyber squatting based on the probability that a certain number of Internet users will mistype the name of a Web site (or actually its URL) when surfing the Web.
• Cyber squatting: The practice of purchasing a domain name that contains a well-known trademark or commercial name. The cyber squatter then offers to sell the domain to the person or company who owns a trademark contained within the name at an inflated price.
• Aircard: Aircard is a device that plugs into a laptop computer, typically through a USB connection or PC Card slot that uses a cell phone signal to provide high-speed Internet access.
• Google Dance: Google dance refers to the Google search engine and their process of re-arranging the rankings of Web sites, and how they are placed in the serps. This happens every 6 - 10 weeks, when Google re-indexes their databases of web-sites.
• Cyberagents: Cyberagents refers to the growing trend of shifting many jobs so that the employee works out of his or her home instead of the office.
• Social bookmarking: Social bookmarking allows consumers to share their favorite bookmarks, Web sites, or content with others by submitting links to a public or semi-public forum.
• Digital footprint: Digital footprint specifically describes the trail which a person leaves behind in cyberspace or on any form of digital communication.
• Hacktivism: A hacktivist is one who combines hacking skills with activism in order to attack (shut down or deface) certain Web sites as a form of political protest.
• CDMA One: CDMA One, also written cdmaOne, refers to the original ITU IS-95 (CDMA) wireless interface protocol that was first standardized in 1993. It is considered a second-generation (2G) mobile wireless technology.
• WCDMA: W-CDMA is a third-generation (3G) mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in today's market.
• CDMA2000: CDMA2000, also known as IMT-CDMA Multi-Carrier or 1xRTT, is a CDMA version of the IMT-2000 standard developed by the International Telecommunication Union (ITU).
• B GAN: BGAN (Broadband Global Area Network) is a mobile communications system created to transmit broadband wireless voice and data communications almost anywhere on the earth's surface except the regions immediately surrounding the north and south geographic poles.
• DVB-H: Digital Video Broadcast - Handheld (DVB-H) is the technology driving mobile TV. A combination of conventional digital video and IP, DVB-H scales for smaller devices a technology that's already in place in millions of TV sets worldwide.
• BREW :BREW (Binary Runtime Environment for Wireless) is Qualcomm's open source application development platform for wireless devices equipped for code division multiple access (CDMA) technology.
• Cellular Telephone: A Wi-Fi cell phone is a cellular telephone that can automatically switch between conventional cellular and Wi-Fi VoIP modes, even during the course of a conversation. A Wi-Fi LAN acts, in effect, as a cellular repeater for such a phone.
• 4G: 4G is the short term for fourth-generation wireless, the stage of broadband mobile communications that will supersede the third generation (3G). End-to-end IP and high-quality streaming video will be among 4G's distinguishing features.
• UMTS:Universal Mobile Telecommunications Service(UMTS) is a third-generation (3G) broadband, packet-based transmission of text, digitized voice, video, and multimedia at data rates up to 2 megabits per second (Mbps).
• HSPDA: High Speed Downlink Packet Access (HSDPA) is a new protocol for mobile telephone data transmission. It is known as a 3.5G (G stands for generation) technology.
• Optical Character Recognition: OCR, optical character recognition refers to the branch of computer science that involves reading text from paper and translating the images into a form that the computer can manipulate. All OCR systems include an optical scanner for reading text and sophisticated software for analyzing images.
• Multi-Function Devices: Devices that combine the functionality of a printer and scanner are called Multi-Function devices. Some multifunction devices can also add additional facilities like that of a dial up modem that can used to fax images scanned with scanner
• Resolution: In computers, resolution is the number of pixels (individual points of color) contained on a display monitor, expressed in terms of the number of pixels on the horizontal axis and the number on the vertical axis.
• Compression: Compression is the reduction in size of data in order to save space or transmission time. For data transmission, compression can be performed on just the data content or on the entire transmission unit (including header data) depending on a number of factors.
• Optical Devices: An optical mouse is an advanced computer pointing device that uses a light-emitting diode (LED), an optical sensor, and digital signal processing (DSP) in place of the traditional mouse ball and electromechanical transducer.
• Flatbed Scanner: A flatbed scanner is usually composed of a glass pane (or platen), under which there is a bright light (often xenon or cold cathode fluorescent) which illuminates the pane, and a moving optical array, whether CCD or CIS.
• ATA / IDE: ATA is a standard interface for connecting storage devices such as hard disks, solid state disks and CD-ROM drives inside personal computers.Many synonyms for ATA exist, including abbreviations such as IDE and ATAPI.
• Mega Pixel:A megapixel refers to one million pixels and is commonly used in reference to digital cameras as an indication of resolution capability. Greater numbers of dots or pixels allow for more refinement of the image, which results in higher, truer image replication.
• Buffer: A Buffer is a temporary storage area, usually in RAM. The key purpose of most buffers is to act as a holding area, so that the CPU can manipulate data before transferring it to a device.
• SATA:Serial Advanced Technology Attachment (SATA) is a computer bus primarily designed for transfer of data between a computer and mass storage devices such as hard disk drives and optical drives.SATA is based on serial signaling technology, unlike current IDE hard drives that use parallel signaling.
• Buffer Underrun Protection: Buffer Underrun Protection is a common problem that occurs when burning data into a CD. It happens when the computer is not supplying data quickly enough to the CD writer for it to record the data properly.
• NAND / NOR FLASH:Flash Memory products are based on two technologies namely NAND and NOR Flash. NAND is used in memory cards such as the Compact Flash cards.NOR is found in lower end set-top boxes, mobile handsets, and BIOS chips.
• Page per Minute (PPM):PPM or Page per Minute is a common method of measuring the output of a printer, as it determines the speed a printer is capable of printing. PPM between different printers cannot be compared on a one-to-one ratio, as you can expect a different PPM number between different types of printers
• Switched-mode power supply(SMPS): A switched-mode power supply or SMPS, is an electronic power supply unit (PSU) that incorporates a switching regulator. This rapidly switches a power transistor between saturation (full on) and cutoff (completely off).
• PictBridge: PictBridge is a standardized technology that allows printing images from a memory card in a digital camera directly to a printer, regardless of brand.The technology completely bypasses the need for a computer.
• Analog-to-digital converter(ADC): An analog-to-digital converter is an electronic integrated circuit, which converts continuous analogue signals to discrete digital numbers or form.The digital output may be using different coding schemes, such as binary, Gray code or two's complement binary.
• Charge-coupled device (CCD):CCD is a light-sensitive integrated circuit that stores and displays the data for an image in such a way that each pixel in the image is converted into an electrical charge the intensity of which is related to a color in the color spectrum.
• Photo Printers: A photo printer is usually an inkjet printer that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.
• HD-DVD / AOD: High-Definition DVD is a new format of optical storage that primarily intended to store High Definition video data. It was also referred to as Advanced Optical Disk.
• Memory Stick: A Memory Stick is an IC (Integrated Circuit) which is stored in a compact and rugged plastic enclosure. Memory Sticks are designed to store data and to enable the transfer of data between devices equipped with Memory Stick slots
• Bad Sector: Hard drives contain millions of sectors. It is very normal for some of these sectors to be bad sectors, even when the drive is first manufactured. In addition, a small number of sectors will normally go bad during the lifespan of a drive
• BIOS/CMOS: BIOS(Basic Input Output System) refers to asset of instructions that are critical for the functioning of the system.CMOS (Complementary Metal Oxide Semiconductor) refers to the chip on which the BIOS instructions are stored.
• Composite Video: Composite video is the most common type of video interface for sending or receiving an analog video signal to or from a television set. In a layman’s language, a type of video signal in which all information—the red, blue, and green signals (and sometimes audio signals as well)—are mixed together.
• Response time: In LCD’s, since the source of light is always on, the concept of refreshing is not applicable. Response time refers to the time it takes the liquid crystal to change shape. Since changing that shape also changes the light passing to the screen, response time is defined in two alternative ways. Black-to-black response time and Grey-to-grey response time
• Ghosting: This phenomenon is seen in LCD’s with a low response time. When dealing with any scene that involves fast motion, pixels that are not quickly updated retains their previous state for a brief moment even as the adjoining pixels have been updated, causing the eye to detect a double image, or “ghost”.
• Hybrid Drives: These are hard drives that include both rotating disks as well as Flash memory based storage. This is an attempt to combine the benefits of the two types of storage media: the inexpensiveness of rotating platters and the non-volatility of Flash memory. The data in a Hybrid Drive is finally written onto the disk as the Flash memory component is a temporary storage area.
• Charge-coupled device (CCD) :CCD is a light-sensitive integrated circuit that stores and displays the data for an image in such a way that each pixel in the image is converted into an electrical charge the intensity of which is related to a color in the color spectrum.
• Photo Printers: A photo printer is usually an inkjet printer that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.
• HD-DVD / AOD: High-Definition DVD is a new format of optical storage that primarily intended to store High Definition video data. It was also referred to as Advanced Optical Disk.
• Memory Stick: A Memory Stick is an IC (Integrated Circuit) which is stored in a compact and rugged plastic enclosure. Memory Sticks are designed to store data and to enable the transfer of data between devices equipped with Memory Stick slots
• Bad Sector: Hard drives contain millions of sectors. It is very normal for some of these sectors to be bad sectors, even when the drive is first manufactured. In addition, a small number of sectors will normally go bad during the lifespan of a drive
• BIOS/CMOS: BIOS(Basic Input Output System) refers to asset of instructions that are critical for the functioning of the system.CMOS (Complementary Metal Oxide Semiconductor) refers to the chip on which the BIOS instructions are stored.
• Composite Video: Composite video is the most common type of video interface for sending or receiving an analog video signal to or from a television set. In a layman’s language, a type of video signal in which all information—the red, blue, and green signals (and sometimes audio signals as well)—are mixed together.
• Response time: In LCD’s, since the source of light is always on, the concept of refreshing is not applicable. Response time refers to the time it takes the liquid crystal to change shape. Since changing that shape also changes the light passing to the screen, response time is defined in two alternative ways. Black-to-black response time and Grey-to-grey response time
• Ghosting: This phenomenon is seen in LCD’s with a low response time. When dealing with any scene that involves fast motion, pixels that are not quickly updated retains their previous state for a brief moment even as the adjoining pixels have been updated, causing the eye to detect a double image, or “ghost”.
• Hybrid Drives: These are hard drives that include both rotating disks as well as Flash memory based storage. This is an attempt to combine the benefits of the two types of storage media: the inexpensiveness of rotating platters and the non-volatility of Flash memory. The data in a Hybrid Drive is finally written onto the disk as the Flash memory component is a temporary storage area.
• GoogleWhack: The goal of a GoogleWhack is to perform search queries that will produce only one single search result in the Google search engine.
• Solid State drive: A solid state drive (SSD) is a data storage device that uses solid state memory to store persistent data. With no moving parts, a solid state drive is usually more robust, effectively eliminating the risk of mechanical failure, usually silent, and usually enjoys reduced seek time and latency by removing mechanical delays associated with hard disk drives.
• Blu-ray Disc: Blu-ray Disc is a next generation optical disc storage media format developed by Sony and others.
• Spoofing: In the IT world, spoofing refers tricking or deceiving computer systems or other computer users.
• Microsoft Surface: Microsoft Surface is a forthcoming multi-touch product from Microsoft which is developed as software and hardware combination technology
• MobileTV?: Mobile TV means bringing the content that is available on TV to mobile phones via mobile telecommunications networks.
  

diffrance between lan and wan

LAN	WAN
LAN stands for local area network.	WAN stands for wide area network.
LAN (Local Area Network) is a computer network covering a small geographic area, like a home, office, or group of buildings	WAN (Wide Area Network) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries
EX: Network in an organization can be a LAN	Internet is the best example of a WAN
Typically owned, controlled, and managed by a single person or an organization	WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management
LANs have a high data transfer rate	WANs have a lower data transfer rate as compared to LANs
A LAN is cheaper than WAN.	WAN is more expensive than LAN.
LAN is note connection oriented.	WAN is connection oriented.
LAN uses the Ethernet standard.	WAN uses the T1 standard.

Internet amazing Facts

• Google got its name from the mathematical figure googol, which denotes the number 'one followed by a hundred zeros'.
• Yahoo! derived its name from the word Yahoo coined by Jonathan Swift in Gulliver's Travels. A Yahoo is a person who is repulsive in appearance and action and is barely human!
• Researchers consider that the first search engine was Archie, created in 1990 by Alan Emtage, a student at McGill University in Montreal, Canada.
• Marc Andreessen founded Netscape. In 1993, he had already developed Mosaic, the first Web browser with a GUI.
• It was once considered a letter in the English language. The Chinese call it a little mouse, Danes and Swedes call it 'elephant's trunk', Germans a spider monkey, and Italians a snail. Israelis pronounce it 'strudels' and the Czechs say 'rollmops's...What is it? The @ sign.
• In the Deep Web, the part of the Web not currently catalogued by search engines, public information said to be 500 times larger than on the WWW.
• The first search engine for Gopher files was called Veronica, created by the University of Nevada System Computing Services group
• Tim Berners-Lee predicted in 2002 that the Semantic Web would "foster global collaborations among people with diverse cultural perspectives", but the project never seems to have really taken off.
• In February 2004, Sweden led the world in Internet penetration, with 76.9 percent of people connected to the Internet. The world average is 11.1 per cent.
• The top visited websites in February2004, including affiliated sites, were Yahoo!, MSN, the Warner Network, EBay, Google, Lycos and About.com.
• The search engine "Lycos" is named for Lycosidae, the Latin name for the wolf spider family.
• The US International Broadcasting Bureau created a proxy service to allow Chinese, Iraians and other 'oppressed' people to circumvent their national firewalls, relaying forbidden pages behind silicon curtains.
• Lurking is to read through mailing lists or news groups and get a feel of the topic before posting one's own messages.
• SRS stands for Shared Registry Server. The central system for all accredited registrars to access, register and control domain names.
• WAIS stands for 'Wide Area Information Servers' - a commercial software package that allow the indexing of huge quantities of information, the makes those indices searchable across the Internet.
• An anonymiser is a privacy service that allows a user to visit Web sites without allowing anyone to gather information about which sites they visit.
• Archie is an information system offering an electronic directory service for locating information residing on anonymous FTP sites.
• On the Internet, a 'bastion host' is the only host computer that a company allows to be addressed directly from the public network.
• 'Carnivore' is the Internet surveillance system developed by the US Federal Bureau of Investigation (FBI), who developed it to monitor the electronic transmissions of criminal suspects.
• Did you know that the original URL of Yahoo! was http://akebono.stanford.edu/ ?
• Developed at the University of Nevada, Veronica is a constantly updated database of teh names of almost every menu item on thousands of gopher servers.
• The Electrohippies Collective is an international group of 'hacktivists' based in Oxfordshire, England.
• UIML (User Interface Markup Language) is a descriptive language that lets you create a Web page that can be sent to any kind of interface device.
• In Internet terminology, a demo is a non-interactive multimedia presentation, the computer world's equivalent of a music video.
• Did you know that the name of the famous search engine AltaVista came into existence when someone accidentally read and suggested the word 'Vista' on an unclean whiteboard as 'Alta Vista'?
• Boeing was the first airline to discover the Y2K problem, way back in 1993.
• Did you know that Domain registration was free until an announcement by the NAtional Science Foundation on 14th September, 1995, changed it?
• The Internet was initially called the 'Galactic network' in memos written by MIT's J C R Licklider in 1962.
• Shokyu Ishiko, a doctorate in agriculture and chief priest of Daioh Temple in Kyoto has created an online virtual temple which will perform memorial services for lost information.
• A 55 kg laddu was made for Lord Venkateswara at Trumala as a Y2K prayer offering.
• The morning after Internet Explorer 4 was released, certain mischievous Microsoft workers left a 10 by 12 foot letter 'e' and a balloon with the message, "We love you", on Netscape front lawn.
• If you were a resident of Tongo, a monarchy in the southwest Pacific, you could own domains as cool as 'mail.to' and 'head.to'.
• The American Registry for Internet Numbers (ARIN) began the administration of Internet IP address in North and South America in MArch 1998.
• The testbed for the Internet's new addressing system, IPv6, is called the 6bone.
• The first Internet worm was created by Robert T.Morris, Jr, and attacked more than 6000 Internet hosts.
• According to The Economist magazine, the first truly electronic bank on the Internet, called First Virtual Holdings, was opened by Lee Stein in 1994.
• The French Culture Ministry has banned the word 'e-mail' in all government ministries, documents, publications and Web sites, because 'e-mail' is an English word. They prefer to use the term 'courriel'.
• The German police sell used patrol cars over the Internet, because earlier auctions fetched low prices and only a few people ever showed up.
• Rob Glasser's company, Progressive Networks, launched the RealAudio system on April 10, 1995.
• 'Broswer safe colours' refer to the 216 colours that are rendered the same way in both the PC and Mac operating systems.
• Though the world Wide Web was born in 1989 at CERN in Switzerland, CERN is mainly involved in research for particle physics.
• The first computer company to register for a domain name was Digital Equipment Corporation.
• The 'Dilbert Zone' Web site was the first syndicated comic strip site available on the Internet.
• Butler Jeeves of the Internet site AskJeeves.com made its debut as a large helium balloon in the Macy's Thanksgiving Day parade in 2000.
• Sun Microsystems sponsors NetDay, an effort to wire American public schools to the Internet, with help from the US government.
• In Beijing, the Internet community has coined the word 'Chortal' as a shortened version of 'Chinese portal'.
• Telnet is one of the oldest forms of Internet connections. Today, it is used primarily to access online databases.
• Domain names can be really sell at high prices! The most expensive domain name was 'business.com', which was bought by eCompanies for $7.5 million in 1999.
• The first ever ISP was CompuServe. It still exists, under AOL Time Warner.
• On an average, each person receives 26.4 e-mails a day.
• Ray Tomlinson, a scientist from Cambrige, introduced electronic mail in 1972. He used the @ to distinguish between the sender's name and network name in the e-mail address.
• Transmission Control Protocol/Internet Protocol (TCP/IP) was designed in 1973.
• The Apple iTunes music store was introduced in the spring of 2003. It allows people to download songs for an affordable 99 cents each.
• Satyam Online become the first private ISP in December 1998 to offer Internet connections in India.
• The number of UK Internet users increase by an estimated 75 percent each yearThe Internet is the third-most used advertising medium in the world, closely catching up with traditional local newspapers and Yellow Pages.
• It took 13 years for television to reach 50 million users- it took the Internet less than 4 years.
• As of now, there are over 260 million people with Internet access worldwide.
• 1 out of 6 people used the Internet in North America and Europe, as per a 1999 survey.
• The average computer user blinks 7 times a minute.
• In 1946, the Merriam Webster Dictionary defined computer as 'a person who tabulates numbers; accountant; actuary; bookkeeper.'
• An estimated 2.5 billion hours were wasted online last year as people waited for pages to download, according to a study sponsored by Nortel Networks.
• AOL says spam is the number one complaint of its customers, and that it has to block over one billion unsolicited e-mails every day.
• In 2002, the average Internet user received 3.7 spam messages per day. The total rose to 6.2 spam messages per day in 2002. By 2007, it is expected to reach 830 messages per day.
• A terminology industry research firm called Basex says that unsolicited e-mail cost $ 20 billion in lost time and expenses worldwide in 2000.
• In 2003 an Atlanta- base ISP called Earthlink won a lawsuit worth $16.4 million (US) against a spammer in Buffalo NY, and a $25 million (US) lawsuit against a spammer in Tennessee.

ECMA International

• ECMA International was founded in 1961.
• The ECMA organization is dedicated to the standardization of Information and Communication Technology (ICT) and Consumer Electronics(CE).
• ECMA has developed standards for
• JavaScript
• C# Language
• International Character Sets
• Optical Disks
• Magnetic Tapes
• Data Compression
• Data Communication
• and much more

Web Services take Web-applications to the Next Level

• By using Web services, your application can publish its function or message to the rest of the world.
•  Web services use XML to code and to decode data, and SOAP to transport it
• (using open protocols).
• With Web services, your accounting department's Win 2k server's billing system can connect with your IT supplier's UNIX server.