
Relational algebra
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The outcome of the data modelling techniques described in Parts 2 and 3 of this book is
a set of tables (i.e. relations) that provide a logical structure for the information of
interest to the enterprise. In order to use this information (for example, to process
borrower registration, loans, returns and reservations in the library example) some
means of manipulating the data is needed.
Relational algebra is a data manipulation language that provides a set of operators,
each of which processes a complete table, or tables, at a time. It is a higher-level
language than those programming languages that ...