Explain the relational database concept with an example.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Open in two lines. A database is an organised collection of related data. A relational database stores it in tables (relations) that are linked by keys.
2 · The data hierarchy. Bit → byte → field → record → table → database.
3 · Tables, records and fields. Each table is about one subject; each row is a record (one customer) and each column a field (City).
4 · Primary and foreign keys.
Primary key: unique ID in its table, e.g. CustomerID.
Foreign key: the same ID placed in another table to link them, e.g. CustomerID in Order.
5 · Draw two linked tables. [Diagram: Customer table (CustomerID, Name, City) linked one-to-many to Order table (OrderID, Date, CustomerID, Amount)]
6 · Advantages over files. Less redundancy, consistent data, easy sharing, central security and backup, and quick queries.
7 · Sri Lankan business example. A supermarket chain links customer, product and sales tables; a loyalty card ID ties every bill to one customer.
8 · Close in one line. Linking tables by keys lets a firm store each fact once and combine data whenever needed.
Scoring tip: Two small sample tables with the keys labelled make the answer clear at a glance.
