W8D1 - Lecture 6

Which SQL clause would you use to apply conditional logic within a query to classify values into different groups?

• GROUP BY

• CASE WHEN

• HAVING

What is the primary difference between the INNER JOIN and LEFT JOIN in SQL?

• INNER JOIN returns all rows from both tables; LEFT JOIN returns only matching rows.

• INNER JOIN returns only matching rows from both tables, while LEFT JOIN returns all rows from the left table and matching rows from the right.

• LEFT JOIN returns all rows from both tables, while INNER JOIN returns only matching rows.

What is the main benefit of using a CTE (Common Table Expression) over a subquery in SQL?

• 1. It allows joining multiple tables in one query.

• 1. It improves readability and allows for better query organization.

• 1. It automatically optimizes query performance.

Which SQL operation allows you to combine the result sets of two or more SELECT statements, ensuring no duplicate records by default?

• UNION

• JOIN

• GROUP BY

When using CASE WHEN in SQL, what does it do?

• It changes the data type of a column.

• It allows for conditional logic to return different results based on specific conditions.

• It removes duplicates from the result set.