DBMS All in One Flashcards

Flashcards generated from DBMS lecture notes for exam review.

Which type of entity cannot exist in the database unless another type of entity also exists?

Weak Entity

What are the different classes of relations created by the technique for preventing modification anomalies called?

Normal Forms

What does a key identify in a database table?

A row.

If a table has been normalized so that all determinants are candidate keys, then the table is in what normal form?

BCNF

What is created when the value of one or more attributes used as a foreign key must exist in another set of one or more attributes in another table?

Referential integrity constraint

A functional dependency is a relationship between or among what?

Attributes

What is the minimal superkey called?

Candidate Key

Where is metadata about the structure of a database stored?

Data dictionary

In the relational model, how are relationships between relations or tables created?

Foreign Keys

What process involves a Cartesian product followed by a selection?

Joins

Functional dependencies are types of constraints based on what?

Keys

What are the logical design of the data and the snapshot of data at a given instance of time, respectively?

Schema, Instance

What order can the tuples of relations be?

Any

Which of the following uniquely identifies a record?

Super Key

What dependency do Tables in Second Normal Form (2NF) eliminate?

Tables have all non-key fields depend on the whole primary key

For each attribute of a relation, there is a set of permitted values, called the what of that attribute?

Domain

What key from one relation is used as an attribute in another relation to form a foreign key?

Primary

Which normal form simplifies and ensures that there is minimal data aggregates and repetitive groups?

3NF

Several entities are associated through what?

relationship

What model represents a collection of tables to represent data and relationships among data?

Relational model

What are the three Armstrong's Axioms?

The Reflexive Rule, The Augmentation Rule, The Transitivity Rule

In the context of database normalization, what are insertion, update, and deletion anomalies?

Problems arising from poorly normalized database designs. Insertion: Cannot add data without adding unrelated data. Update: Updating one piece of data requires updating multiple records. Deletion: Deleting a record unintentionally removes related data.

When designing a database, what dependencies should be considered to achieve 2NF?

clientID-> cLName, cFName, cAddress are partial dependencies.

In relational algebra, how do you query wookie Jedi on the light side?

Needs algebraic Expression

Does the relational model provide logical and physical independence?

Yes, the relational model provides both logical and physical independence.

In normalization, what is the first step to check for 2NF in a relation?

Find the candidate keys

What does a certificate value on movies mean?

Movies will be given only one certificate

Why is it good or bad to have redundant data in a database?

Data Availability: Redundancy can increase data availability and reliability. If one instance of the data becomes corrupted or unavailable, other copies can still be used, enhancing fault tolerance.
Data Inconsistency: Redundant data can lead to data inconsistency. If one copy of the data is updated while others are not, it can result in conflicting information within the database. This makes maintaining data integrity more challenging.

What normal form is the BOOK relation in (BOOK (Booktitle, Authorname, Booktype, Listprice, Author_affil, Publisher))?

The given relation is in 1NF (1st Normal Form)

Is the following decomposition lossless? D = {R1 (M, Y, P); R2 (M, MP, C)}

Yes, the decomposition D is lossless.

Why the table is not in 2NF if Primary Key is (doctorID, patientID) where doctorID -> doctorName?

Because doctorID -> doctorName. So here is partial dependency

What type of entity cannot exist in the database unless another type of entity also exists?

Weak Entity

A recursive relationship is a relationship between an entity and what?

Itself

Which of the following is NOT True regarding Weak Entity?

None of the given

Which of the following is True regarding Associative entity?

All of the given

If the attribute AGE is calculated from DATE OF BIRTH, what type of attribute is AGE?

Derived Attribute

An attribute that identifies an entity is called what?

Identifier

Which of the following indicate the maximum number of records that can be involved in a relationship?

Maximum Cardinality

In which of the following can one entity instance of one type be related to many entity instances of another type?

One to Many relationship