Relation Algebra|computer science

Relation Algebra|computer science

1. The following database

Supply (Company, part, Qty)

Storage (Department, part, Qty)

find all parts and their quantity used by “ computer science” department.

find all firms which supply at least one part used by” computer science” department

find all firms supply all the parts be “ computer science” department.

2. The following database

deposit (bank_account, account_number, costumer_name, balance)

barrow (bank_name, last_ name, costumer_name, account)

Find all customers who have only a deposit account whose balance is greater than $ 1000.

Find all customers who have only a deposit account at (Chester) branch and whose balance greater than $ 2500.

Find all customers who have both a deposit account and a loan at (Chester) branch.

3. One of the set operators (-x) can be expressed in terms of the other set operators .

which one is it? give the algebraic expression in terms of the other set operators.

hint: R S = (RS) x (R-S)

4. give an algebraic expression for the join operation in terms of other relation algebra operations.

5. Do the operations balance customers? (, , , , , -, )

6. Under what condition is the following equation true ?

A1(R)= R

: means the number of tuples.

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