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Tom Chapman

on 23 October 2009

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Transcript of Databases

Databases What is a database? A database is a collection of records which are made up of different pieces of data and information. a database does not have to be on a computer
it can also be created on a paper based format such
as a phonebook A computer based databsase is used in exactly the same way as a paper based one but when the user wants to find something the database will automatically find it instead of the user having to search for a long time Tables databases store information in tables Records A record is all of the data or information about one person or one thing.

In the table , all of the information about each cartoon character is stored in a 'row' or 'record'.
Fields A field is a type of information in a database, such as an address or a first or last name. Data Types There are many different data types these can include alphanumeric or text( allows you to insert numbers text and symbols), currency(amounts of money), Number(just numbers alone), Boolean (yes or no answers), autonumber (this will automatically increase by 1 for each record), date and time(this is restricted to only the date and time) primary key A primary key is the type of field that is used to uniquely identify each record so that there is no confusion field length The field length is the maximum size of a database
and how many records the database can hold Validation As well as choosing the correct data types to try to reduce the number of errors made when entering data into the database, there is another method that can be used when setting up the table. This is called 'Validation'.

It is very important to remember that Validation cannot stop the wrong data being entered, you can still enter 'Smiht' instead of 'Smith' or 'Brown' instead of 'Green' or '78' instead of '87'.

What Validation can do, is to check that the data is sensible, reasonable and allowable.
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