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1. What is a SQL JOIN?

A SQL query to retrieve data from a single table.

A SQL query to retrieve data from multiple tables.

A SQL query to update data in a table.

A SQL query to delete data from a table.

2. Which type of JOIN returns only the common rows between two tables?

INNER JOIN

LEFT JOIN

RIGHT JOIN

FULL OUTER JOIN

3. What is a self-join?

A join between two different database systems.

A join that involves the same table.

A join that uses subqueries.

A join between two unrelated tables.

4. Which SQL JOIN returns all rows from the left table and the matched rows from the right table?

INNER JOIN

LEFT JOIN

RIGHT JOIN

FULL OUTER JOIN

5. What is a subquery in SQL?

A query that retrieves data from multiple tables.

A query that updates data in a table.

A query that deletes data from a table.

A query nested inside another query.

6. Which SQL operator is used to compare a subquery result to a single value?

BETWEEN

#NAME?

7. What does the SQL EXISTS operator do?

It checks if a subquery returns any rows.

It counts the number of rows in a subquery.

It compares two columns for equality.

It checks if a column exists in a table.

8. Which type of subquery returns multiple rows of data?

Scalar subquery

Correlated subquery

Non-correlated subquery

Row subquery

9. What is a correlated subquery in SQL?

A subquery that references columns from the outer query.

A subquery that retrieves data from multiple tables.

A subquery that uses the EXISTS operator.

A subquery that returns a single value.

10. What is the purpose of the SQL UNION operator?

To combine rows from two or more tables.

To retrieve data from a single table.

To sort data in ascending order.

To group data by a specified column.

11. Which SQL JOIN returns all rows from both tables, with NULL values in columns where there is no match?

INNER JOIN

LEFT JOIN

RIGHT JOIN

FULL OUTER JOIN

12. What is the purpose of the SQL INTERSECT operator?

To combine rows from two or more tables.

To retrieve data from a single table.

To retrieve rows that are common to two result sets.

To retrieve distinct values from a table.

13. What does the SQL HAVING clause do?

It filters rows before grouping.

It filters rows after grouping.

It performs table joins.

It specifies the order of rows.

14. Which SQL JOIN returns all rows from the right table and the matched rows from the left table?

INNER JOIN

LEFT JOIN

RIGHT JOIN

FULL OUTER JOIN

15. What is the purpose of the SQL UNION ALL operator?

To combine rows from two or more tables.

To retrieve data from a single table.

To retrieve rows that are common to two result sets.

To combine rows from two or more SELECT statements, including duplicates.

16. Which SQL operator is used to filter rows based on a pattern match in a text column?

UPDATE

BETWEEN

17. What is the purpose of the SQL EXCEPT operator?

To combine rows from two or more tables.

To retrieve data from a single table.

To retrieve distinct values from a table.

To retrieve rows that are in the first result set but not in the second.

18. What is the primary difference between UNION and UNION ALL in SQL?

UNION returns distinct values, while UNION ALL includes duplicates.

UNION ALL returns distinct values, while UNION includes duplicates.

UNION excludes NULL values, while UNION ALL includes NULL values.

UNION ALL is used for text columns, while UNION is used for numeric columns.

19. In SQL, what does the JOIN condition specify?

The order of columns in the result set.

The columns to be included in the SELECT clause.

The criteria for matching rows from different tables.

The grouping of rows based on a specified column.

20. What is the purpose of the SQL GROUP BY clause?

To filter rows based on a specified condition.

To combine rows from multiple tables.

To retrieve distinct values from a column.

To group rows based on one or more columns and apply aggregate functions.

21. Which SQL operator is used to specify a range of values in a WHERE clause?

BETWEEN

IS NULL

22. In SQL, what is a subquery used for?

To update data in a table.

To retrieve data from a single table.

To retrieve data for use in another query.

To sort data in ascending order.

23. What does the SQL ORDER BY clause do?

It specifies the columns to be included in the SELECT clause.

It filters rows based on a specified condition.

It specifies the order of rows in the result set.

It groups rows based on a specified column.

24. What is the purpose of the SQL DISTINCT keyword?

To filter rows based on a specified condition.

To combine rows from multiple tables.

To retrieve distinct values from a column.

To group rows based on a specified column.

25. In SQL, what does the JOIN ON clause specify?

The order of columns in the result set.

The columns to be included in the SELECT clause.

The criteria for matching rows from different tables.

The grouping of rows based on a specified column.

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Questions

1. What is a SQL JOIN?
Answer: A SQL query to retrieve data from multiple tables.
Explanation: A SQL JOIN is used to combine data from multiple tables into a single result set.Report for correction

2. Which type of JOIN returns only the common rows between two tables?
Answer: INNER JOIN
Explanation: An INNER JOIN returns only the rows that have matching values in both tables being joined.Report for correction

3. What is a self-join?
Answer: A join that involves the same table.
Explanation: A self-join is a join where a table is joined with itself, typically using aliases to distinguish between the two instances of the same table.Report for correction

4. Which SQL JOIN returns all rows from the left table and the matched rows from the right table?
Answer: LEFT JOIN
Explanation: A LEFT JOIN returns all rows from the left table and the matched rows from the right table. If there are no matches, NULL values are returned for the right table's columns.Report for correction

5. What is a subquery in SQL?
Answer: A query nested inside another query.
Explanation: A subquery is a query that is embedded inside another query and is used to retrieve data for further processing.Report for correction

6. Which SQL operator is used to compare a subquery result to a single value?
Answer: IN
Explanation: The IN operator is used to compare a subquery result to a set of values, and it returns rows that match any value in the set.Report for correction

7. What does the SQL EXISTS operator do?
Answer: It checks if a subquery returns any rows.
Explanation: The EXISTS operator is used to check if a subquery returns any rows. It returns TRUE if the subquery result is not empty.Report for correction

8. Which type of subquery returns multiple rows of data?
Answer: Non-correlated subquery
Explanation: A non-correlated subquery returns multiple rows of data and is independent of the outer query.Report for correction

9. What is a correlated subquery in SQL?
Answer: A subquery that references columns from the outer query.
Explanation: A correlated subquery is a subquery that references columns from the outer query, allowing it to be dependent on the outer query.Report for correction

10. What is the purpose of the SQL UNION operator?
Answer: To combine rows from two or more tables.
Explanation: The UNION operator is used to combine rows from two or more SELECT statements or tables into a single result set.Report for correction

11. Which SQL JOIN returns all rows from both tables, with NULL values in columns where there is no match?
Answer: FULL OUTER JOIN
Explanation: A FULL OUTER JOIN returns all rows from both tables and includes NULL values in columns where there is no match.Report for correction

12. What is the purpose of the SQL INTERSECT operator?
Answer: To retrieve rows that are common to two result sets.
Explanation: The INTERSECT operator is used to retrieve rows that are common to two result sets.Report for correction

13. What does the SQL HAVING clause do?
Answer: It filters rows after grouping.
Explanation: The HAVING clause is used to filter rows after grouping has been performed, typically in combination with the GROUP BY clause.Report for correction

14. Which SQL JOIN returns all rows from the right table and the matched rows from the left table?
Answer: RIGHT JOIN
Explanation: A RIGHT JOIN returns all rows from the right table and the matched rows from the left table. If there are no matches, NULL values are returned for the left table's columns.Report for correction

15. What is the purpose of the SQL UNION ALL operator?
Answer: To combine rows from two or more SELECT statements, including duplicates.
Explanation: The UNION ALL operator is used to combine rows from two or more SELECT statements, including duplicate rows.Report for correction

16. Which SQL operator is used to filter rows based on a pattern match in a text column?
Answer: LIKE
Explanation: The LIKE operator is used to filter rows based on a pattern match in a text column using wildcard characters.Report for correction

17. What is the purpose of the SQL EXCEPT operator?
Answer: To retrieve rows that are in the first result set but not in the second.
Explanation: The EXCEPT operator is used to retrieve rows that are in the first result set but not in the second result set.Report for correction

18. What is the primary difference between UNION and UNION ALL in SQL?
Answer: UNION returns distinct values, while UNION ALL includes duplicates.
Explanation: The primary difference is that UNION removes duplicate rows from the combined result set, while UNION ALL includes all rows, including duplicates.Report for correction

19. In SQL, what does the JOIN condition specify?
Answer: The criteria for matching rows from different tables.
Explanation: The JOIN condition specifies the criteria for matching rows from different tables in a SQL join operation.Report for correction

20. What is the purpose of the SQL GROUP BY clause?
Answer: To group rows based on one or more columns and apply aggregate functions.
Explanation: The GROUP BY clause is used to group rows based on one or more columns and apply aggregate functions to the grouped data.Report for correction

21. Which SQL operator is used to specify a range of values in a WHERE clause?
Answer: BETWEEN
Explanation: The BETWEEN operator is used to specify a range of values in a WHERE clause.Report for correction

22. In SQL, what is a subquery used for?
Answer: To retrieve data for use in another query.
Explanation: A subquery is used to retrieve data for use in another query, often as a condition for filtering or matching rows.Report for correction

23. What does the SQL ORDER BY clause do?
Answer: It specifies the order of rows in the result set.
Explanation: The ORDER BY clause is used to specify the order in which rows should be displayed in the result set.Report for correction

24. What is the purpose of the SQL DISTINCT keyword?
Answer: To retrieve distinct values from a column.
Explanation: The DISTINCT keyword is used to retrieve unique (distinct) values from a column in the result set.Report for correction

25. In SQL, what does the JOIN ON clause specify?
Answer: The criteria for matching rows from different tables.
Explanation: The JOIN ON clause specifies the criteria for matching rows from different tables in a SQL join operation.Report for correction

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