•On it’s own 110913 means nothing – it’s just a piece of data. •You need to add format/structure and context to data for it to make sense – this gives the data Meaning. •For example: -110913 = data -11/09/13 = data with format/structure which now tells us this is a date -11/09/13 = this is the date of the ICT exam next year •If we know what data means we have Information. Data + Meaning = Information Height - Real Est Age - Integer Hair Colour - Alphanumeric Eye colour - Alphanumeric Gender - Boolean The information school stores about me is kept in a Record as part of a database. Each piece of information they keep about me is stored in a Field. Two examples of fields used by school to store my inforamtion are medical records and detentions. Files records and fields.1.What is a KEY FIELD? A field that is unique for a particular record 2.Give an example of a key field. Date of birth 3.Why are these needed? To make each record unique 4.What is a FLAT FILE database? They only contain one table of data 5.List one advantage of flat file databases. Easy to understand 6.List two disadvantages of flat file databases. Non unique records and lots of duplicates of records 7.What is a RELATIONAL database? When data is stored in a table with several links between the tables. 8.List two advantages of relational databases. Data is only stored once and complex queries 9.List one disadvantage of relational databases. Expensive to set up and certain data can jumble up. What is a key field? A unique piece of data in a record also known as a primary key. What is a flat file database? A database which consists of only one table. What is a relational database? A relational database consists of more than one table in one file. What is Data? Data is raw facts and figures, data on its own has no meaning. E.g d243 b2.2 853 ldor4 These are all example of data as they have no meaning. Different Data Types:
Logical or Boolean •Data stored in boolean form can only be one of two available values. •Think of a light switch – it’s on or off. Examples include: Yes, No True, False M,F Alphanumeric •Alphanumeric data is any combination of letters, numbers and symbols (@#¬|\/>< etc.) •This data type is also known as a string or text. •Alphanumeric or text/string is used to hold telephone numbers. •In a computer, telephone numbers are stored as text. •This is because the telephone number contains a leading zero and spaces. E.g: &*&!£@:< dqwu 344 i like fish Real: A real number is one which has decimal places. E.g: 1579.24 53.5 65.787339 6.64 Integer: Integer numbers are whole number, no bits, no decimal places. E.g 235876 -45 36 Date •Dates can be stored in many different forms. •In the UK we write the date in the form DD/MM/YYYY e.g. 31/12/2014. •In the US, they use the form MM/DD/YYYY e.g. 12/31/2014. E.g 15/08//1855 2004/04/27 11/18/1953 Other data types: •Currency – Software will automatically add £ or $ to data and include decimal places. E.g. £22.99. •Images/Sound Bites/Video Clips – Some databases will allow an images, sound and video clips to be stored. For example a photo of a criminal and their fingerprints on a crime database. |
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