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Database Terminology 1. A database is A collection of data or information which is held together in an organised or logical way 2. An example of a paper-based database is Address book Birthday book Yellow pages Any other sensible answer 3. Three examples of computerised databases are Search engines e.g. Google Electronic school registers Library database of books and loans Police criminal database Any other sensible answer 4. Computerised Vs paper-based databases: Computerised database Can hold a vast amount of data Very fast to search for a record Can be easily amended or updated Records are stored safely Data can be easily sorted on multiple criteria Can easily analyse data e.g. most popular item sold Easy to make a backup Paper-based database Can only hold what can be stored in a limited physical space Can take a long time to manually search through records Changes have to be done manually – can look untidy Records can be lost or misfiled Not easy to sort on more than one criteria Difficult to analyse data Making up-to-date backups is time consuming 5. Explain why a database is suitable for storing information • • • • • Vast amounts of information can be stored Queries can be run to search for a specific records or group of records Reports can be produced from the data stored or queries Information can be extracted and exported into a word processing package for mail merging Validation can be used to reduce errors © www.teach-ict.com All Rights Reserved 6. A database table stores Information in the form of records 7. A record is All of the data or information about one person or one thing 8. An example of a record might look like Title Mrs Forename Sally Surname Chadwick Date of Birth 14/05/62 9. A record is made up of fields. A field is One piece of data or information about a person or thing 10. Two examples of fields might be First name Eye colour Height Any sensible answer 11. Explain what is meant by a ‘flat-file database’ A database which contains only one table. 12. Explain what is meant by the term ‘data duplication’ Where data is unnecessarily repeated 13. List the problems that may occur as a result of using a flat-file database Data duplication can result in a much larger database than necessary More hard disk space is needed to store the database Data duplication makes the database slower to search High risk of data entry errors as the same data has to be entered repeatedly 14. Explain how a relational database can overcome the problems of a flat-file database. To overcome the problems with flat file databases and reduce data duplication, relational databases are used. Data is split up into sensible groups and a separate table is made for each group. © www.teach-ict.com All Rights Reserved 15. Define the term, ‘primary key’ The primary key is a field in a table which allows each record to be uniquely identified. 16. Give two examples of a primary key Customer ID Product ID Driving licence number Bank account number Hospital patient number Any sensible answer 17. List three things which are important about a primary key Each record must have a primary key The primary key must be unique to that record You should be able to identify any record by its primary key. 18. Explain what is meant by a ‘simple primary key’ and give an example A simple primary key is made up of a single field only e.g. customer number 19. Explain what is meant by a compound or composite primary key and give an example A compound / composite primary key combines more than one field to make a unique value. e.g. each card in a deck would be identified by its suit and its value – Ace of Hearts 20. Define the term, ‘secondary key’ A secondary key is made on a field that you would like to be indexed for faster searches. A table can have more than one secondary key. 21. Define the term, ‘foreign key’ A foreign key is used to link tables together and create a relationship. It is a field in one table that is linked to the primary key in another table 22. Explain what is meant by ‘referential integrity’ Every foreign key value has a matching value in the corresponding primary key. Referential integrity uses these to ensure that there are no orphan records i.e. it prevents you from deleting related records. Foreign key – customer ID in rentals table, primary key – customer ID in customer table © www.teach-ict.com All Rights Reserved