What is the purpose of the SELECT operation in relational algebra?

To select a subset of tuples from a relation that satisfies a selection condition.

What does the PROJECT operation do?

It selects certain columns from a relation and discards the others.

What are the three standard set operations in relational algebra?

UNION, INTERSECTION, and SET DIFFERENCE (MINUS).

What is the CARTESIAN PRODUCT operation?

It combines every member from one relation with every member from another relation.

What is the JOIN operation used for?

To combine related tuples from two relations into single tuples.

A join where the only comparison operator used is equality (=).

What is a NATURAL JOIN?

A join that automatically combines attributes with the same name from two relations.

What is the DIVISION operation in relational algebra?

It is used to find tuples in one relation that are related to all tuples in another relation.

What is the difference between relational algebra and relational calculus?

Relational algebra is procedural, specifying how to retrieve data, while relational calculus is declarative, specifying what data to retrieve.

What is the purpose of normalization in database design?

To eliminate redundancy and ensure data integrity by organizing data into tables.

What is the first normal form (1NF)?

A relation is in 1NF if all its values are atomic, meaning no repeating groups or nested relations.

What is the second normal form (2NF)?

A relation is in 2NF if every non-prime attribute is fully functionally dependent on the primary key.

What is the third normal form (3NF)?

A relation is in 3NF if it is in 2NF and no non-prime attribute is transitively dependent on the primary key.

What is a functional dependency?

A relationship where one attribute uniquely determines another attribute.

What is a primary key?

An attribute or a set of attributes that uniquely identifies a tuple in a relation.

What is a candidate key?

A minimal set of attributes that can uniquely identify a tuple in a relation.

What is a prime attribute?

An attribute that is part of a candidate key.

What is a non-prime attribute?

An attribute that is not part of any candidate key.

What is an insertion anomaly?

A problem that occurs when certain attributes cannot be inserted into a relation without including other attributes.

What is a deletion anomaly?

A problem that occurs when deleting a tuple results in losing important information.

What is a modification anomaly?

A problem that occurs when changing a value in one tuple requires changes in multiple tuples.

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

To group rows that have the same values in specified columns into summary rows.

What is the HAVING clause used for in SQL?

To filter groups based on a specified condition after aggregation.

What is the ORDER BY clause used for in SQL?

To sort the result set of a query by one or more columns.

What is the purpose of the INSERT statement in SQL?

To add new tuples to a relation.

What is the purpose of the UPDATE statement in SQL?

To modify existing tuples in a relation.

What is the purpose of the DELETE statement in SQL?

To remove tuples from a relation.

What is a view in SQL?

A virtual table that is derived from one or more base tables.

What is the purpose of the CREATE VIEW statement?

To define a new view in the database.

A query nested inside another SQL query.

What is the purpose of the EXISTS keyword in SQL?

To test for the existence of rows returned by a subquery.

What is the purpose of the IN keyword in SQL?

To check if a value matches any value in a list or subquery.

What is the purpose of the NOT EXISTS keyword in SQL?

To test for the non-existence of rows returned by a subquery.

What is the purpose of the COUNT function in SQL?

To return the number of tuples that match a specified condition.

What is the purpose of the SUM function in SQL?

To return the total sum of a numeric column.

What is the purpose of the AVG function in SQL?

To return the average value of a numeric column.

What is the purpose of the MAX function in SQL?

To return the maximum value of a column.

What is the purpose of the MIN function in SQL?

To return the minimum value of a column.

What is the purpose of the DISTINCT keyword in SQL?

To return only unique values in the result set.

What is a trigger in SQL?

A set of instructions that are automatically executed in response to certain events on a particular table.

What is a stored procedure in SQL?

A precompiled collection of SQL statements that can be executed as a single unit.

What is the purpose of the ALTER TABLE statement?

To modify the structure of an existing table.

What is the purpose of the DROP TABLE statement?

To remove a table and all its data from the database.

What is the purpose of the GRANT statement in SQL?

To give specific privileges to users on database objects.

Basic Math Flashcards Flashcards

Student preview

149 questions

Show all answers

1.

FLASHCARD QUESTION

Front

What is 2 + 2?

Back

4

2.

FLASHCARD QUESTION

Front

What is the square root of 16?

Back

4

3.

FLASHCARD QUESTION

Front

What is 5 * 6?

Back

30

4.

FLASHCARD QUESTION

Front

What does a NULL value for a primary key imply?

Back

It implies that we cannot identify some tuples, making it difficult to distinguish between them.

5.

FLASHCARD QUESTION

Front

What are key constraints and entity integrity constraints?

Back

They are specified on individual relations to ensure that each tuple can be uniquely identified.

6.

FLASHCARD QUESTION

Front

What is a referential integrity constraint?

Back

It is specified between two relations to maintain consistency among tuples, ensuring that a tuple in one relation refers to an existing tuple in another.

7.

FLASHCARD QUESTION

Front

What is a foreign key?

Back

A set of attributes in one relation that references the primary key of another relation.

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