Bank Relational Database Consider the bank database of Figure 2. Give an express

Question

Bank Relational Database Consider the bank database of Figure 2. Give an expression in relational algebra for each of the following queries. Find all courses offered by TTU. List only those courses such that at least one person took the course. Do not use a "count" aggregate. Solve the problem with joins. Your list of courses should be unique. Answer: Find all students that have take a course on a campus that has more students than, at least, one other campus. Again, you will not need any type of aggregate function. You will need to use the rename operator rho. Answer: Show all instructors that do not have the maximum or the minimum salary. Again, you will not need any type of aggregate function. You will need to use the rename operator rho. Answer:

Explanation / Answer

To organize the data, first the redundant data and repeating groups of data are removed, which we call normalized. By doing this the data is organized or normalized into what is called first normal form (1NF). Typically a logical data model documents and standardizes the relationships between data entities (with its elements). A primary key uniquely identifies an instance of an entity, also known as a record.

Once the data is normalized and in sets of data (entities and tables), the main operations of the relational algebra can be performed which are the set operations (such as union, intersection, and cartesian product), selection (keeping only some rows of a table) and the projection (keeping only some columns). Set operations are performed in the where statement in SQL, which is where one set of data is related to another set of data.

In addition, the Cartesian product is defined differently from the one in set theory in the sense that tuples are considered to be "shallow" for the purposes of the operation. That is, the Cartesian product of a set of n-tuples with a set of m-tuples yields a set of "flattened" (n + m)-tuples (whereas basic set theory would have prescribed a set of 2-tuples, each containing an n-tuple and an m-tuple). More formally, R

Related Questions

Navigate

• Browse (All)
• Browse B
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.