Data Types
Data is processed by computers, the resulting information can then be used to make decisions.
Data is words, numbers, dates, images, sounds etc without context i.e. Data consists of raw facts and figures.
This is a list of data items:
- 34
- mango
- 15.05
- lion
- $12
- 12:00
- rat
Information is a collection of words, numbers, dates, images, sounds etc put into context, ie to give them meaning.
For example, When data items used to form part of a sentence they gain meaning:
- There are 34 mangoes in that box and each one of them has been nibbled by rats.
- The fare to the seaside is $12 and the journey takes 34 minutes by rail.
- My telephone number is 123456. Call me at 15.05.
Information can then be used to produce knowledge, by applying rules to it.
Data Types
Data can be stored in many formats called 'data types'. When setting up a database or spreadsheet, it is important that the correct data type is selected for each field. This is because the data type will determine what can be done with the data held in that field e.g. sorting, searching, calculations etc.
Data can be of different types-
- Text (alphanumeric)- A text data type can hold any letter, number, symbol or punctuation mark. It is sometimes referred to as 'alphanumeric' or 'string'. The data can be pure text or a combination of text, numbers and symbols.
- Numeric (real)- Your numerical data might need to be formatted with decimal places. This means it cannot be stored as an integer number. Instead it is known as a 'real' number. You can specify the number of decimal places that you need.
- Numeric (Integer)- An integer stores whole numbers, either positive or negative. Integers however cannot store numbers with decimal places.
- Currency- When you choose to format numerical data as currency then it will automatically be given two decimal places. The currency data type also allows you to display the correct currency symbol such as $.
- Dates- When you choose to format dates.
- Calculated - used to hold calculated values like an average of percentile.
- Pictures- used to store pictures and images
- Sounds- used to store audio
- Boolean/Logical
- Moving graphics /Video Clips
- A database consists of a number of related files (sometimes called tables).
- A file consists of a number of related records.
- A record consists of a number of related fields.
- A field is a single data item consisting of a number of characters.
Database
A database is a collection of data that you want to manage, rearrange, and add to later. It is a good program to use to manage lists that are not entirely numbers, such as addresses and phone numbers, inventories, and membership rosters. With a database you could sort the data by name or city or postal code or by any individual item of information recorded. You can create forms to enter or update or just display the data. You can create reports that show just the data you are interested in, like members who owe dues.
Both spreadsheets and databases can be used to handle much the same information, but each is optimized to handle a different type most efficiently. The larger the number of records, the more important the differences are.
Examples of databases: MS Access, dBase, FoxPro, Paradox, Approach, Oracle, Open Office Base.
Purpose: Managing data
Major Advantages:Can change way data is sorted and displayed
Types of databases
- Flat database: The earliest and simplest databases are flat databases. A flat database may still be all you need for your purpose.
Advantages:- Easy to set up
- Easy to understand
Disadvantages:
- May require entering the same information in many records.
- A text database is hard to read.
- A single record in a spreadsheet database may not fit across the screen.
- Relational database: Microsoft Access and Oracle and other relational databases are more advanced and more efficient. This kind of database uses a set of tables which are linked together. Using a well-designed relational database can greatly reduce the amount of data you must enter each time you add a record. For large numbers of records, a relational database can search through the records faster. A 'relational' database is one that contains two or more tables of data, connected by links called relationships.
Advantages:- Reduces the duplication in data entry
- Faster searches
- Can create forms and reports that display only the data you want to see
- Can create queries to answer questions that are hard or impossible to answer in flat databases
- Can be complex to set up, using many tables
- It is harder to understand how all the parts relate to each other
A text database is a plain text file where the fields are separated by a particular character. A text database is hard to read in this raw form. A database program can show each record separately in a more readable display. It is hard to create a report that contains just the parts you want to see.
A spreadsheet can work as a flat database. Each field is in a separate column and each row is a single record. You cannot use two rows for one record.
- Data processing involves transforming raw facts and isolated figures into timely, accurate, and useful information.
- The conversion of data into information is accomplished through a cycle of events identified as input, process, and output.
- During input, data are collected and organized to simplify subsequent processing functions. During processing, input data are mathematically manipulated or logically arranged to generate meaningful output. The output can be reported for immediate use or saved for future reference.
Important Data Processing Modes:
- Batch Processing: A batch processing system is where programs or data are collected together in a batch and processed in one go. Typically the processing of payrolls, electricity bills, invoices and daily transactions are dealt with this way.
This method of operation lends itself to jobs with similar inputs, processing and outputs where no human intervention is needed. Jobs are stored in a queue until the computer is ready to deal with them. Often batch processed jobs are done overnight.
Producing Monthly Payrolls, Producing Gas Bills, Producing utility bills, Inputting details of new stock into a library’s database, Reading data from bank cheques and Scanning OMR Sheets are the examples of Batch Processing. - On-line/Real-time processing: Data is processed so quickly that the results are able to influence the activity currently taking place.
Advantages of Each Method:
- The main advantage of batch processing was efficiency in processing.
- On-line data entry is more accurate than periodic batch input because the system can refuse incomplete of erroneous entries.
- Real-time processing ensures that the information in master files is always current.
Data, Signal, Signalling and Transmission
In data communication, four basic terms Data, Signal, Signalling and Transmission are frequently used.
- We define Data as enities that convey meaning i.e. raw facts.
- Signals are electric or electromagnetic encoding of data.
- Signalling is the act of propagation of signal along with suitable communication medium.
- Transmission is communication of data by the propagation and processing of signals.
Analogue and Digital Signals
One of the fundamental concepts in data communication is to understand the difference between analogue and digital signals.
- An Analog Signal is one that is continuous with respect to time, and mat take on any value i.e. positive as well as negative, within a given range of values.
Human voice, video and music when converted to electrical signal using suitable transducers produce analog signals. - A Digital signal may take on only a discreteset of values withing a given range. Everything stored and processed inside a computer is a digital.
Need of Signal Conversion
Computers are unable to process analogues signals because they are digital devices. For digital devices such as computers, to work with analogue devices such as sensors, conversion is required...
In order to use an analog signal on a computer it must be digitized with an analog-to-digital converter. A digital-to-analog converter is used to convert the digital signal back to analog. The use of a digital computer is a key ingredient in digital control systems.
- Analogue to Digital Convertor (ADC) is a device which is used to convert analog signals into digital signlas.
If you want to attach an analogue input device to a digital device such as a computer, you will need an analogue to digital convertor (ADC).
A good example of a computer peripheral that requires an ADC is a microphone. When you plug a microphone into a computer, you are actually plugging it into an ADC which converts the analogue signals from the microphone into digital data that the computer can then process. - Digital to Analogue Convetor (DAC) is a device which is used to convert digital signals into analogue signals.
If you want to attach an analogue output device to a digital device such as a computer, you will need a digital to analogue convertor (DAC).
A good example of a computer peripheral that requires a DAC is a loudspeaker or headphones. When you plug a loudspeaker into a computer, you are actually plugging it into a DAC, which takes digital data from the computer and converts it into analogue signals which the loudspeaker then converts into sound.
Another device that contains a DAC is an MP3 player. The music data stored in the player is all digital, but the player produces analogue signals which the headphones convert into sound.
