1Z0-006 Fundamental Database Concepts 4 — Questions and Answers
Question 1: What is the primary purpose of database normalization?
- To maximize query performance by denormalizing data
- To reduce data redundancy and improve data integrity (Correct answer)
- To increase the number of tables for better indexing
- To simplify backup and recovery operations
Correct answer: To reduce data redundancy and improve data integrity
Normalization organizes data to minimize redundancy and dependency, preventing update, insert, and delete anomalies.
Question 2: In an Entity-Relationship (ER) diagram, what does a diamond shape represent?
- An entity
- An attribute
- A relationship (Correct answer)
- A primary key
Correct answer: A relationship
In ER diagrams, diamond shapes represent relationships (associations) between entities, while rectangles represent entities and ovals represent attributes.
Question 3: What is a non-correlated subquery?
- A subquery that references columns from the outer query
- A subquery that executes independently of the outer query (Correct answer)
- A subquery that always returns exactly one row
- A subquery placed in the SELECT clause only
Correct answer: A subquery that executes independently of the outer query
A non-correlated subquery executes once independently and passes its result to the outer query, unlike a correlated subquery which references outer query columns.
Question 4: Which Oracle SQL function returns the current date and time including fractional seconds and timezone?
- SYSDATE
- CURRENT_DATE
- SYSTIMESTAMP (Correct answer)
- NOW()
Correct answer: SYSTIMESTAMP
SYSTIMESTAMP returns the current date and time including fractional seconds and the database timezone, while SYSDATE returns only date and time without fractional seconds.
Question 5: What is a composite primary key?
- A primary key created using a database sequence
- A primary key composed of two or more columns together (Correct answer)
- A primary key that also serves as a foreign key
- A primary key defined at the table level, not column level
Correct answer: A primary key composed of two or more columns together
A composite primary key uses multiple columns in combination to uniquely identify each row, where no single column alone provides uniqueness.
Question 6: What does the term 'schema' refer to in Oracle Database?
- The physical storage layout on disk
- A collection of database objects owned by a database user (Correct answer)
- The SQL script used to create a database
- The network configuration for database connections
Correct answer: A collection of database objects owned by a database user
In Oracle, a schema is the collection of all objects (tables, views, indexes, sequences, etc.) that belong to a particular database user.
Question 7: Which type of database model stores data in nodes connected by edges, making it ideal for social networks?
- Relational model
- Hierarchical model
- Graph model (Correct answer)
- Document model
Correct answer: Graph model
A graph database model uses nodes (entities) and edges (relationships) to store data, excelling at traversing complex relationship networks like social graphs.
1Z0-006 Fundamental Database Concepts 4
What is the primary purpose of database normalization?