Normalization in Relational Databases Quiz

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In the context of the EMP_PROJ relation, what is an example of an insert anomaly?

A project being inserted multiple times with different project numbers

An employee being inserted with incorrect employee number format

Unable to insert an employee without assigning them to a project

Unable to insert a project without assigning an employee to it (correct)

What is the main issue caused by storing redundant information in tuples in relational databases?

No impact on storage costs but causes data inconsistency

Decreased storage costs and faster data retrieval

Improved data integrity and faster query performance

Increased storage costs and update anomalies (correct)

What is the consequence of a delete anomaly in the EMP_PROJ relation?

Deletion of an employee results in the deletion of all projects associated with that employee

Deletion of a project results in the deletion of all employees associated with that project (correct)

Mismatched project numbers and employee ids after a deletion operation

Inability to delete any tuples from the EMP_PROJ relation

How does storing redundant information impact data consistency and integrity in relational databases?

It leads to data inconsistency and compromises data integrity Signup and view all the answers

What is the specific update anomaly described in the context of the EMP_PROJ relation?

Changing the name of a project for all employees working on that project Signup and view all the answers

What is the purpose of functional dependencies in relational designs?

To constrain the meaning and interrelationships of the data attributes Signup and view all the answers

Which statement best describes the concept of a superkey?

A set of attributes with the property that no two tuples will have the same value for those attributes Signup and view all the answers

What does it mean for one attribute to be prime and another to be nonprime in the context of keys?

Prime attributes are part of the primary key, while nonprime attributes are not part of any key Signup and view all the answers

Which of the following is true about candidate keys in a relation schema?

Each candidate key is arbitrarily designated as the primary key Signup and view all the answers

In the context of normalization, what does it mean for a relation to be in a particular normal form?

The relation has been decomposed into smaller relations Signup and view all the answers

What does the SQL aggregation operation 'count' do?

Counts the number of non-null values in the specified column Signup and view all the answers

Which aggregation operation applies to a single attribute in SQL?

count Signup and view all the answers

What is the purpose of 'group by' in SQL aggregation?

To apply aggregate functions to multiple attributes Signup and view all the answers

In SQL, how can you calculate the total cost of purchases for a specific product?

SELECT avg(price * quantity) FROM Purchase WHERE product = 'specific product' Signup and view all the answers

When should 'count(DISTINCT column)' be used in SQL aggregation?

To count the number of unique values in the specified column Signup and view all the answers

In SQL, what is the purpose of the HAVING clause?

To filter rows based on a specified condition after the GROUP BY clause has been applied Signup and view all the answers

What does a NULL value typically represent in SQL?

An unknown value Signup and view all the answers

Which SQL statement is used to permanently delete one or more rows from a table?

DELETE FROM table_name WHERE [condition]; Signup and view all the answers

What is the purpose of the GROUP BY clause in SQL?

To group rows that have the same values into summary rows Signup and view all the answers

What is the purpose of the SELECT DISTINCT statement in SQL?

To select only unique values from a column or set of columns Signup and view all the answers