17 Questions
Which operation in relational algebra allows for selecting a subset of rows based on certain conditions?
Selection
What does the UNION operation in relational algebra do?
Combine two relations
In grouping data, what does the GROUP BY clause do?
Produces a single summary row for each group
Which statement about GROUP BY in SQL is correct?
GROUP BY may contain all the GROUP BY expressions
When adding additional fields to the projection list, what must be done in SQL?
Include them in the GROUP BY clause
What are the conditions that a primary key should satisfy?
Is representative in the problem context
What is the purpose of a foreign key in a relational database?
To link two tables by referencing the primary key of one table in another
How is referential integrity ensured when inserting a record in a secondary table?
By ensuring that the corresponding key exists in the referenced table
What is a common solution to handling deadlocks in relational databases?
Using late checking of constraints
What is the purpose of integrity constraints in a database schema?
To ensure that logical expressions are satisfied by any instance of the database
In database design, what is the function of a primary key?
To ensure uniqueness of tuples in a relation
What is the difference between a key and a superkey in the context of relational databases?
A key ensures uniqueness, while a superkey includes at least one key
At which level of abstraction is the data described in terms of its physical storage and location?
Physical level
What does the term "cardinality" refer to in the context of a relational database?
The number of distinct records in a relation
In the context of a relational database, what is the "degree" of a relation?
The number of attributes in a relation
What is the primary purpose of an integrity constraint in a relational database?
To enforce data integrity rules
When setting up referential integrity between two tables, what does the foreign key in one table typically refer to?
Primary key in another table
Learn about the step-by-step process of creating a new page in Oracle APEX, including tasks such as running table visualizations, data editing forms, showing the primary key, and adding new records. Follow the instructions provided to understand the page creation workflow.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
