Final Take 2.2

Question 1

What is a combination of product, selection and (optionally) projection?

Answer 1

Join

Question 2

SELECT * FROM A INNER JOIN B;

Answer 2

Product

Question 3

Partial specialization

Answer 3

Specifies that an entity instance of a supertype does not require an instance of a subtype

Question 4

HAVING

Answer 4

finds all groups meeting stated conditions

Question 5

referential integrity and it’s importance

Answer 5

Referential integrity requires that any values for a foreign key be from the set of values from
the related primary key. Referential integrity is important because it ensures that data is
consistent between primary key and foreign key relationships

Question 6

ACID

Answer 6

Atomicity: A transaction is considered an atomic unit; all changes in a transaction are made or none of the changes are made.
Consistency: Statements in a transaction must leave the database in a consistent state by not
violating any data constraints.
Isolation: An in-process transaction will not be impacted by other users. Likewise, any
changes made during an in-process transaction will not be seen by other users until the
transaction is resolved.
Durability: Once a transaction is committed, the changes are considered permanent.