1. GCSE Computing#BristolMet Session Objectives# 20 MUST describe a database and discuss the legal implications of storing personal information SHOULD explain the use of logical operators in framing database queries COULD create methods of validating data as it is input. Create a customised user interface to automate functionality such as searching and amending the database

2. GCSE Computing#BristolMet Key Words

3. Database File Table Record Field Data Type Value This is the main file that holds the entire database. It’s usually saved on a hard drive or network server but can be saved on a portable storage device. A table is a collection of data about a specific topic, i.e table of student names and addresses There can be many tables in a single database. When these tables are linked together it is known as a relational database. A group of fields which are related in some way, i.e a student record could be: Surname, Forename, Date of Birth, Tutor Group etc. Individual data items with their own data type are known as fields. An example is a Date of Birth field (NB its data type will be Date) Data types are the properties of each field. Each field only has one data type – this aids storage and searching facilities. A value is each individual data entry, occupying one cell, i.e, for the student record example, it could be just a students’ Surname. Database Schema

4. GCSE Computing#BristolMet Data Types Test Mr Smith 38 High Street, Weston – Super – Mare Somerset BS23 6AR (0117) 9236666 JohnSmith@yahoo.co.uk 1/11/05 Number 1 2 3 4 6 Text Alpha Numeric – Text or Memo Hyperlink 7 Date/Time 5 Text

5. GCSE Computing#BristolMet Logical Operators < <= = > >= <> Less than Less than or equal to Equal to More than More than or equal to Not equal to

6. GCSE Computing#BristolMet Use of Logical Operators Write the following statements using logical operators Less than £200 Greater than £300 Equal to or more than £500 Less than or equal to £150 Greater than £225 Everything that is not equal to £250

7. GCSE Computing#BristolMet Database Interrogation This is the technical term for searching a database or querying. TASK: Complete the Customer Enquires tasks on the travel agent database. EXTENSION: Customer Enquiries 2

8. GCSE Computing#BristolMet Data Validation This means to only allow sensible or valid data into the system at the point of entry. There are many methods which can be used to reduce the chance of data entry errors. Can you think of any?? Format check or Input Mask – e.g. 2 letters then 2 numbers – PR15 would be valid. Presence check – checking that the field contains data. Range check – data is between certain numbers or letters, e.g. A–E. Lookup check – only values from a set list can be entered, e.g. M or F. Size check – checking data is more or less than a minimum or maximum number of characters.