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Primary Key (1 of 2) |   |
Software - Databases
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A primary key is a field which contains data which is unique for each record in a particular table. For example, a library may have a database to store information about its stock of books: Considering each column in turn we can see that an author can have written more than one book, two different books may have the same title, a publisher can have published more than one book, and a year will have more than one book published in it.
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