What does the following relational algebra expression represent ?
Consider the relations given below with keys in Bold :
Branch (branch no, street, city)
Staff (staff No, name, salary, branch No, position, DOB)
propertyForRent (property No, staff No, rent)
Answer this query in relational algebra :
List the Staff Numbers of Staffs who have not rent any property
- ΠstaffNo (Staff) - Π propertyNo (propertyForRent)
- Π staffNo (Staff) U Π staffNo (propertyForRent)
- Π staffNo (Staff) - Π staffNo (propertyForRent)
- Π staffNo (Staff) * ΠstaffNo(rent)