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COMPUTING
Relational Database 1
A flat file database has a single table - each row or record represents one of the entites in the database. Each field represents an attribute of that entity.
The flat file has some severe limitations. For instance if it is a database of orders, each order may contain several items. Whilst these items are entities in their own right, the constraints of the flat file system cause them to be entered as attributes of the order. Some records will have more fields than others. Relational database theory is all about the concepts that make the database a better abstraction of real world issues, and normalisation of a database is the design process that improves the abstraction.
A first normal form (1NF) database has no repeated fields. Records for the repeating entities are stored in their own table. A relationship between two members of the different tables is established by including the primary key reference to one record as a 'foreign key' field in the other table.
Where the relation is one to many, and not many to many, (for example a bespoke tailor makes each garment for a particular customer, who may order many garments) the two tables are all that is required for first normal form, with the garment table including the foreign key field to identify the customer.
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