Understanding Database Keys and Dependencies

Šta je primarni ključ u bazi podataka?

• Kolona koja je uvek obavezna

• Kolona koja čuva tekstualne podatke

• B) Kolona koja jedinstveno identifikuje svaki red u tabeli

• Kolona koja može biti indeksirana

Šta predstavlja pojam 'strani ključ'?

• Ključ koji identifikuje jedinstvene vrednosti u bazi podataka

• Ključ koji se koristi za enkripciju podataka

• Ključ koji predstavlja jedinstveni identifikator za korisnika

• C) Kolona koja se koristi za povezivanje sa primarnim ključem druge tabele

Koja od sledećih zavisnosti ukazuje da atribut B zavisi od atributa A?

• B ↔ A

• A → B

• A + B

• A ⊇ B

Šta je tranzitivna zavisnost?

• C) Kada atributi ne zavise jedni od drugih

• B) Kada atribut A zavisi od atributa B, a B zavisi od C

• D) Kada su svi atributi nezavisni

• A) Kada jedan atribut direktno zavisi od drugog

Koji od sledećih primera najbolje ilustruje funkcionalnu zavisnost?

A) Student_ID → Ime B) Ime → Student_ID

• Kurs → Student_ID

• Student_ID → Kurs

• A) Student_ID → Ime

• Ime → Godine

What is the purpose of a composite key? A) To combine multiple columns to create a unique identifier B) To link two tables together C) To sort data in a specific order D) To allow NULL values in a table

• E) To encrypt sensitive data

• G) To create indexes for faster queries

• F) To define relationships between columns

• A) To combine multiple columns to create a unique identifier

What is a candidate key? A) A key that can be used as a primary key B) A key that is not unique C) A key that is always NULL D) A key that links to another table

• A) A key that can be used as a primary key

• A key that is always unique

• A key that can be used for indexing

• A key that is derived from a foreign key

What is the difference between a primary key and a unique key? A) A primary key can have duplicates, while a unique key cannot B) A unique key can accept NULL values, while a primary key cannot C) Both are the same D) A primary key is used for sorting, while a unique key is not

• B) A unique key can accept NULL values, while a primary key cannot

• D) A unique key is used for sorting, while a primary key is not

• C) Both can have duplicates

• A) A primary key can be null, while a unique key cannot

What is a surrogate key? A) A key that is derived from the data B) A key that is created for convenience and has no business meaning C) A key that is always NULL D) A key that is used to link tables

• A key that is always unique

• A key that is derived from a primary key

• B) A key that is created for convenience and has no business meaning

• A key that is used for data validation

What does normalization in databases aim to achieve? A) To reduce redundancy and improve data integrity B) To increase the size of the database C) To make data retrieval slower D) To allow for more NULL values in tables

• To create duplicate entries for each record

• To eliminate all data from the database

• A) To reduce redundancy and improve data integrity

• To enforce strict data types without exceptions