Posted by admin on 1st March 2010

Databases

You can be pretty much certain that you will get a question that involves databases in your GCSE ICT exam. You definitely need to revise the topic so you can be confident in answering those questions.

A database is a program that’s used to store data – it has to be able to create a structure to store data, sort it in different orders, search through it to select data that’s most helpful and output data in different formats. There are some key terms that you need to know for databases – words that questions and teachers will use in class. Make sure you know what they mean and practice explaining them clearly.

Database
Table
Field
Record
Data type
Query
Report

Databases are a really important topic because they’re everywhere! From storing your reward card details at the supermarket, to the Police storing DNA and details of criminals to banks, hospitals, they’re everywhere! You might get asked a question about how databases might be used in different scenarios. You’ll need to think about the data that might be stored and what kind of searches and printed outputs that would be needed.

A full page of data on a database is called a “table”. It’s made up of “records” and “field”. When you look at a full table of data, you’ll see a record as a row across a database. It’s all the data about that one single thing – perhaps one of the houses in a database for an estate agent. Each of the cells in that row is a field – like “price” and “number of bedrooms”.

For each field you have to pick what type of data is allowed – once you’ve chosen, it will restrict what you can enter into that field.

Datatype What can I type?
Number Only numbers – it could be decimals (e.g. 5.673) or integers (whole numbers like 42)
Currency Prices only – you can change it from Pounds to Dollars or Euros, but it’s still only going to have two decimal places – like £4.99
Date/time Date/time might have a date or a time. It can be formatted in lots of different ways. It could be like 22/02/10 14:27
Text (or alphanumeric) This datatype is not just about letters. Text means anything a keyboard can type – and alphanumeric, its other name has alphabet and numbers in it. Ideal for addresses or postcodes with numbers or letters, and in fact anything that might need a letter in it at all.
Yes/no Often displayed as a tick box, this datatype makes it easy to answer a question as true or false.

There are often questions about searching or queries. Simple queries might have one condition or criteria that you’re searching for. They may use symbols like < for “less than” or > for “greater than”. For example, an estate agent might need to find houses that cost less than £100,000 with a criteria like

price < 100000

Sometimes you’ll need more than one criteria to find what you’re looking for. Perhaps the estate agent might add to the previous query like this:

price < 100000 and bedrooms = 2

Which will find all the houses less than £100,000 that have 2 bedrooms.

There’s always more to find out about this topic – start by clicking on this link to search for more web pages about databases

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