Relational Algebra

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Across
  1. 3. The result of this operation, denoted by R – S, is a relation that includes all tuples that are in R but not in S.
  2. 6. Denoted by ÷, is useful for a special kind of query that sometimes occurs in database applications.
  3. 7. It represents input relations of the query as leaf nodes of the tree, and represents the relational algebra operations as internal nodes.
  4. 8. A function used to count for counting tuples or values.
  5. 10. The result of this operation, denoted by R ∪ S, is a relation that includes all tuples that are either in R or in S or in both R and S.
  6. 12. Uses the symbol I(pronounced as script F)
  7. 14. The basic set of operations for the formal relational model.
  8. 15. The result of this operation, denoted by R ∩ S, is a relation that includes all tuples that are in both R and S.
Down
  1. 1. Is used to combine related tuples from two relations into single “longer” tuples.
  2. 2. Denoted as "x". produces a new element by combining every member (tuple) from one relation (set) with every member (tuple) from the other relation (set)
  3. 4. Selects certain columns from the table and discards the other columns
  4. 5. The SELECT operator is -------; that is, it is applied to a single relation.
  5. 9. The operation is used to choose a subset of the tuples from a relation that satisfies a selection condition.
  6. 11. Denoted as "*" which is used to get rid of superfluous attribute.
  7. 13. A JOIN, where the only comparison operator used is "=" is used.