In SQL, which clause is used to combine rows from two or more tables based on a related column?

• A. LEFT JOIN
• B. INNER JOIN
• C. GROUP BY
• D. ORDER BY

Answer: (B)

The INNER JOIN clause is used in SQL to combine rows from two or more tables based on a related column between them. When you utilize INNER JOIN, it returns only the rows from each table that have matching values in the related columns. This means that if there is no match found in one of the tables, those records will not be included in the result set.

For instance, if you have a customers table and an orders table, utilizing an INNER JOIN on a common column (like customer_id) will yield a result that displays only those customers who have placed orders. Thus, INNER JOIN is essential for retrieving related data spread across different tables, ensuring that the output is meaningful and directly connected through the specified relationships.

The other choices serve different purposes: LEFT JOIN would include all records from one table and matched records from another, while GROUP BY is used for aggregating data, and ORDER BY is meant for sorting results. These functionalities do not specifically facilitate the combination of rows based on a related column as INNER JOIN does.