weaknesses from midterm 2

Question 1

When does an INNER Join occur?

Answer 1

You join two tables based on values in one table being equal to values in another table.

Question 2

What happens to an inner join when no values exist for a given attribute in a record participating in the operation

Answer 2

The join does not return that specific record in the result.

Question 3

Do every single TABLE in the relational model qualify as a RELATION?

Answer 3

The short answer is No.

To qualify strictly as a relation, a table must meet certain conditions (such as each row being unique, each column having a unique name, no repeating groups, etc.). If a table violates these conditions (for example, by having duplicate rows, non-atomic values, or ordering assumptions), then it technically doesn’t qualify as a “relation” in the strict relational-model sense—even though in practice, we often still call it a “table.”

Question 4

A RELATION in the relational model correponds in the ER Diagram to:

Answer 4

Entity Types

AND

Many-to-Many Relationship Types

Question 5

What is it called when the primary key on the one side becomes a foreign key on the many side?

Answer 5

One-to-Many

Question 6

What is the relationship for this scenario: “Create a new relation with the primary keys of the two entities as its primary key”

Answer 6

Many-to-Many

Question 7

When mapping binary relatwionships from ER diagrams into relations “the primary key on the mandatory side becomes a foreign key on the optional side?”

Answer 7

One-to-One

Question 8

What are functional dependencies?

Answer 8

Functional dependencies describe a relationship where one attribute (or a set of attributes) uniquely determines another attribute in a relation.