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Unsourced material may be challenged and removed. A relational database is a digital database based on the relational model of data, as proposed by E.
Rows are also called records or tuples. Columns are also called attributes. Each row in a table has its own unique key. Codd showed that data relationships of arbitrary complexity can be represented by a simple set of concepts.
Part of this processing involves consistently being able to select or modify one and only one row in a table. System performance is optimized for PKs.