Podcast
Questions and Answers
Which operation in relational algebra allows for selecting a subset of rows based on certain conditions?
Which operation in relational algebra allows for selecting a subset of rows based on certain conditions?
- Set difference
- Selection (correct)
- Cartesian product
- Projection
What does the UNION operation in relational algebra do?
What does the UNION operation in relational algebra do?
- Discard duplicates from the result
- Tuples in R1, but not in R2
- Combine two relations (correct)
- Select a subset of rows from a relation
In grouping data, what does the GROUP BY clause do?
In grouping data, what does the GROUP BY clause do?
- Produces a single summary row for each group (correct)
- Selects the maximum value in a group
- Orders the groups based on a specified criteria
- Adds additional fields to the projection list
Which statement about GROUP BY in SQL is correct?
Which statement about GROUP BY in SQL is correct?
When adding additional fields to the projection list, what must be done in SQL?
When adding additional fields to the projection list, what must be done in SQL?
What are the conditions that a primary key should satisfy?
What are the conditions that a primary key should satisfy?
What is the purpose of a foreign key in a relational database?
What is the purpose of a foreign key in a relational database?
How is referential integrity ensured when inserting a record in a secondary table?
How is referential integrity ensured when inserting a record in a secondary table?
What is a common solution to handling deadlocks in relational databases?
What is a common solution to handling deadlocks in relational databases?
What is the purpose of integrity constraints in a database schema?
What is the purpose of integrity constraints in a database schema?
In database design, what is the function of a primary key?
In database design, what is the function of a primary key?
What is the difference between a key and a superkey in the context of relational databases?
What is the difference between a key and a superkey in the context of relational databases?
At which level of abstraction is the data described in terms of its physical storage and location?
At which level of abstraction is the data described in terms of its physical storage and location?
What does the term "cardinality" refer to in the context of a relational database?
What does the term "cardinality" refer to in the context of a relational database?
In the context of a relational database, what is the "degree" of a relation?
In the context of a relational database, what is the "degree" of a relation?
What is the primary purpose of an integrity constraint in a relational database?
What is the primary purpose of an integrity constraint in a relational database?
When setting up referential integrity between two tables, what does the foreign key in one table typically refer to?
When setting up referential integrity between two tables, what does the foreign key in one table typically refer to?
