A-level Computing 2009/AQA/Problem Solving, Programming, Operating Systems, Databases and Networking/Databases/Databases

Primary keys Table In our database we will store information about 'things', or more technically, entities. To store data about things we use Tables. Each table will store data about a particular thing. Let's look at two examples: Database: Crime in a local area Tables: Crimes, Victims, Criminals, Police Officers And looking at another example that you might be familiar with, a social networking site: Database: Social Network Tables: People, Relationships, Messages, Pictures 1 Exercise: Picking Tables List the tables you might need to store a database on a football League Team Player Match Stadium Referee List the tables you might need to record details for an online store Staff Products Receipts Customers Attribute/Field Now we have gotten to grips with recognising the main tables we need to store in each database, we need to recognise what fields of data will be stored in each of these tables. The data items to be stored are called the attributes. Taking the Criminal database as an example: Table: Criminal Attributes: Name: String Date of Birth: Date Number of scars: Integer Home town: String Note that for each of the attributes we are listing the attribute name and the field type, when building a database it is very important that we get the correct field type to prevent errors when entering data. Let's take a look at another example from the criminals Database Table: Crimes NI Number: String Description: String Type of crime: String Severity: Integer Date of Crime: Date Victim ID: Integer Criminal ID: Integer 1 Exercise: Picking attributes For a social networking site, what attributes and data types would you include for the table of people Name: string Date of Birth: Date Gender: string (character might also work here) Public profile: boolean Personal description: String For a social networking site, what attributes and data types would you include for the table of relationships (the table that stores 'friend' 'sister' 'father' etc) Person1 ID: integer Person2 ID: integer Type of relationship: string Date created: Date Records