Aggregation Operators

Extended Operators of Relational Algebra

An Algebra of Relational Operations presented the classical relational algebra, and Relational Operations on Bags introduced the modifications required to treat relations as bags of tuples rather than sets. The ideas of these two sections serve as a base for most of

Full-Relation Operations

In this section we shall look at some operations that act on relations as a whole, rather than on tuples individually or in small numbers (as do joins of various relations, for example). First, we deal with the fact that SQL uses relations that are bags rather than sets, and a tuple can

Grouping / HAVING Clauses

To group tuples, we use a GROUP BY clause, following the WHERE clause. The keywords GROUP BY are followed by a list of grouping attributes. In the simplest situation, there is only one relation reference in the FROM clause, and this relation has its tuples grouped according

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