Hello I need some help with all of these multiple choice questions. Thank you!

$11.$ Which of the following is an advantage of a snowflake schema compared to a star schema?

a$.$ Simpler queries

b$.$ Reduced data redundancy

c$.$ Increased performance

d$.$ Easier visualization

$12.$ What does the UNION ALL operator do in SQL$?$

a$.$ Combines two queries and removes duplicates

b$.$ Combines two queries without removing duplicates

c$.$ Returns the intersection of two queries

d$.$ Returns the Cartesian product of two queries

$13.$ Which scenario is most suited to using a graph database?

a$.$ Analyzing sales transactions

b$.$ Modeling hierarchical data like a company organization chart

c$.$ Recommending products based on purchase patterns

d$.$ Tracking real$-$time social network interactions

$14.$ Which of the following is not a valid SQL data type?

a$.$ BOOLEAN

b$.$ STRING

c$.$ INTEGER

d$.$ FLOAT

$15.$ What does the EXCEPT operator do in SQL$?$

a$.$ Combines results from two queries and removes duplicates

b$.$ Returns rows present in the first query but not the second

c$.$ Returns rows present in both queries

d$.$ Returns the Cartesian product of two queries

$16.$ Which of these ensures a column value matches a specific format in SQL$?$

a$.$ CHECK constraint

b$.$ FOREIGN KEY constraint

c$.$ DEFAULT constraint

d$.$ INDEX

$17.$ Which relational algebra operation returns tuples from one relation that do not

appear in another?

a$.$ Division

b$.$ Difference

c$.$ Projection

d$.$ Selection

$18.$ Which property of ACID ensures data consistency when multiple transactions

occur simultaneously?

a$.$ Atomicity

b$.$ Consistency

c$.$ Isolation

d$.$ Durability

$19.$ Which of the following best describes ETL in a data warehousing context?

a$.$ A process for real$-$time querying of operational data

b$.$ A method for encrypting and securing sensitive data

c$.$ The sequence of Extracting, Transforming, and Loading data into a warehouse

d$.$ A strategy for partitioning large datasets across multiple servers

$20.$ Which command in SQL rolls back a transaction?

a$.$ SAVEPOINT

b$.$ COMMIT

c$.$ ROLLBACK

d$.$ BEGIN TRANSACTION