What does the “x” operator do in relational algebra?a)Outp...
The “x” operator outputs all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes). This operation is called as the Cartesian product operation and is similar to the Cartesian product of sets.
What does the “x” operator do in relational algebra?a)Outp...
Explanation:
Relational Algebra Operator:
The "“x”" operator in relational algebra is known as the Cartesian product, denoted by x. It combines every tuple from one relation with every tuple from another relation, resulting in a new relation with all possible combinations of rows from both input relations.
Output Description:
- The operator outputs all pairs of rows from the two input relations, regardless of whether or not they have the same values on common attributes.
- Each row from the first relation is combined with every row from the second relation, resulting in a cross-product relation where each tuple is a combination of one row from the first relation and one row from the second relation.
Example:
Consider two relations R(A, B) and S(C, D) where R has 2 tuples (r1, r2) and S has 3 tuples (s1, s2, s3). The cross-product R x S will contain 6 tuples:
- (r1, s1), (r1, s2), (r1, s3), (r2, s1), (r2, s2), (r2, s3)
Usage:
- The Cartesian product is used when there is a need to combine every tuple from one relation with every tuple from another relation, such as in generating all possible combinations or when there is no common attribute for a join operation.
Conclusion:
The "“x”" operator in relational algebra outputs all pairs of rows from the two input relations, creating a new relation with all possible combinations of rows from both input relations.
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