1Z0-006 Database Concepts & Terminology 2 — Questions and Answers
Question 1: Which term describes the complete set of data values that an attribute can legally hold?
- Tuple
- Domain (Correct answer)
- Schema
- Instance
Correct answer: Domain
A domain defines the set of permissible values for an attribute, such as integers between 1 and 100 or valid date values.
Question 2: In relational database terminology, a row in a table is also called a:
- Attribute
- Relation
- Tuple (Correct answer)
- Domain
Correct answer: Tuple
A tuple is the formal relational term for a single row or record within a relation (table).
Question 3: What is a 'schema' in the context of a relational database?
- The actual data stored in the database at a given moment
- The structural definition of the database including tables and relationships (Correct answer)
- A backup copy of the database
- A query used to retrieve data
Correct answer: The structural definition of the database including tables and relationships
A schema is the logical structure or blueprint of the database, defining tables, columns, data types, and constraints without reference to actual data values.
Question 4: Which concept ensures that every row in a table can be uniquely identified?
- Foreign key
- Primary key (Correct answer)
- Index
- Constraint
Correct answer: Primary key
A primary key is a column or combination of columns whose values uniquely identify each row in a table and cannot be NULL.
Question 5: A foreign key in a relational database is used to:
- Speed up query performance
- Encrypt sensitive data
- Establish a link between data in two tables (Correct answer)
- Define the data type of a column
Correct answer: Establish a link between data in two tables
A foreign key creates a referential link between a column in one table and the primary key of another table, enforcing referential integrity.
Question 6: What does 'data redundancy' mean in database design?
- Data that is encrypted and stored twice
- The same data being stored in multiple places unnecessarily (Correct answer)
- Data backed up to a secondary server
- Columns with duplicate names in different tables
Correct answer: The same data being stored in multiple places unnecessarily
Data redundancy refers to the unnecessary duplication of data across the database, which wastes storage and can lead to inconsistency during updates.
Question 7: Which of the following best defines an 'entity' in database design?
- A column in a database table
- A real-world object or concept about which data is stored (Correct answer)
- A SQL query that retrieves records
- A constraint applied to a table
Correct answer: A real-world object or concept about which data is stored
An entity is a distinguishable real-world object or concept—such as a person, place, or event—that has data stored about it in the database.
1Z0-006 Database Concepts & Terminology 2
Which term describes the complete set of data values that an attribute can legally hold?