Question

The HAVING-clause of an SQL retrieval query can only appear with a GROUP BY-clause:

a. True
b. False

Answer 1

The HAVING clause in SQL retrieval query can be used with or without a GROUP BY clause.

Step-by-step explanation:

The correct answer is b. False. The HAVING clause in an SQL retrieval query is used to filter the results of a query based on a condition applied to a group of rows. It can be used without a GROUP BY clause to filter the results based on an aggregate function result, or it can be used with a GROUP BY clause to filter the groups based on a condition.

For example, consider a table of students with columns 'name', 'age', and 'score'. To retrieve the names of students with an average score greater than 80, the query can be written as 'SELECT name FROM students HAVING AVG(score) > 80;'. In this case, the HAVING clause is used without a GROUP BY clause.

Therefore, it is not necessary for the HAVING clause to appear with a GROUP BY clause in an SQL retrieval query.