Topic 8 - Information Handling Software

Topic 8 - Information Handling Software

1. Data Types

   • Number (integer): a whole number (positive or negative) but no fractions e.g. 43
   • Number (real): any number, including whole numbers and fractions e.g. 220.719
   • String (text): letters, numbers or other characters such as punctuation marks e.g. John Smith!
   • Currency: money, including foreign currencies e.g. £,$
   • Boolean: two opposite states e.g. true or false.
   • Lists: a list of values, sometimes called a drop down. Only data from this list can be selected.
   • Picture: image data from a digital camera, mobile phone, the internet, a clip-art library or scanned image.
   • Sound: a beep from a barcode reader or popular song.
   • Video: a video introduction to computer game or a download film/TV programme.

2. Files, records and fields

   • A field is a single item of data within a record e.g. date of birth
   • A record consists of a collection of related fields e.g. a pupil's record in a school database only has fields related to that pupil and no other pupil's data.
   • A file (known as a table in Microsoft Access) is a collection of related fields.

3. Validation Checks

   • Range check: the data entered must be within a sensible range e.g. if a test is out of 100 marks then only marks in the range 0-100 are acceptable.
   • Type check: this ensures that the data is if the correct type e.g. if the number of rooms in a house is being recorded then only and integer will be accepted.
   • Format/picture check: if the data entered has a particular pattern then an input mask can be used to force the data to conform e.g. input mask for a database would be LLN NLL for a postcode.
   • Data entered into a database must be sensible or we get GIGO. Validation checks ensure that reasonable and sensible data is input into a system. It does not ensure data is correct.
   • Length check: the length of the input is checked for the number of characters used.
   • Presence check: checks that necessary data has been entered e.g. if you were ordering something online and you didn't enter your address, you would not receive your item.
   • Lookup list: if the data entered consists of a limited number of possible entries then the computer can compare the entry with a list of allowed answers.

4. Key Terms

   • Date/time: any time or date; the way the time or date is displayed depends on the format e.g. 04/10/15 or 12:15pm
   • Reports: a report is a printed document that contains data from the database, organised and analysed in a certain way.
   • Forms: forms are used to make data entry more attractive and secure rather than entering data into raw tables.
   • Calculated fields: not all data needed in a report may be present in a database. for example a person's age is never included in a database because it changes day by day. if you want to use age in a report it must be calculated. this result is known as calculated field.
   • Uses of a database: add, change and delete records, search for a particular item, sort the records into an order and print reports about some aspect of the database.
   • updating records: records do not stay the same forever. they will need to be updated at some point. for example, people get married and change their surname, people move and change ther address or prices of goods change.
   • searching for data: one main use aof a database is to find information quickly. to search for information you use a query. you are querying the database. a query specifies what records you are searching for and what fields from the records you wouldlike to display.