база

Which SQL clause is used to filter results after aggregation has been performed?

• WHERE

• SELECT

• GROUP BY

• HAVING

What happens if you use the INTERSECT keyword between two SQL queries?

• The result set includes rows that are present in both queries

• The result set includes rows from the first query but not thesecond

• The result set excludes all duplicate rows

• The result set includes all rows from both queries

Which of the following operators is used to combine the result sets of two or more SELECT queries, removing duplicates?

• UNION

• EXCEPT

• JOIN

• INTERSECT

Which keyword is used in SQL to create a virtual table that is based on the result-set of a query?

• INDEX

• VIEW

• FUNCTION

• TABLE

Which SQL command is used to delete a view?

• ALTER VIEW view_name;

• DROP VIEW view_name;

• REMOVE VIEW view_name;

• DELETE VIEW view_name;

In the context of subqueries, which statement is correct?

• A subquery must always return multiple rows

• A subquery cannot be used with DELETE statements

• A subquery is only used to insert data

• A subquery is a query within another query

Which of the following is NOT a set operation in SQL?

• CONNECT

• EXCEPT

• INTERSECT

• UNION

What is a natural join in SQL?

• A join that produces a Cartesian product

• A join that automatically matches columns with the same names in both tables

• A join that filters data based on a selection condition

• A join that includes all rows from both tables

Which aggregate function returns the number of non-null records in a column?

• AVG ()

• SUM ()

• COUNT ()

• MAX ()

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

• To sort the result set

• To remove duplicates

• To group rows that have the same values in specified columns

• To filter rows