To answer this question, we need to understand the purpose of the GROUP BY clause in SQL.
The GROUP BY clause is used to group rows in a table based on one or more columns. It is often used in conjunction with aggregate functions (such as SUM, COUNT, AVG, etc.) to perform calculations on groups of data.
Let's go through each option to determine which one denotes the GROUP BY clause:
Option A) having - The HAVING clause is used to filter the results of a query based on a condition that applies to groups created by the GROUP BY clause. It is used after the GROUP BY clause and aggregate functions. While the HAVING clause is related to the GROUP BY clause, it does not denote the GROUP BY clause itself.
Option B) group by - The GROUP BY clause is used to group rows in a table based on one or more columns. This option correctly denotes the GROUP BY clause.
Option C) where - The WHERE clause is used to filter rows in a table based on a condition. It is used before the GROUP BY clause and does not denote the GROUP BY clause itself.
Option D) both 1 and 2 - Option D is correct because it includes both the HAVING clause (option A) and the GROUP BY clause (option B), which together form the group clause in SQL.
Therefore, the correct answer is option D.