Which of the following statement is correct about the following SQL query?
SELECT CourseName, Fees, StartDate, Duration FROM Students, Courses
WHERE Students.CourseID = Courses.CourseID
GROUP BY BookID

The correct answer is Option 1) It is a wrong query as attribute in the GROUP BY clause is not specified in the SELECT clause.

Key Points

• In SQL, when using the GROUP BY clause, all selected columns that are not aggregated must appear in the GROUP BY clause.
• In the given query:

  SELECT CourseName, Fees, StartDate, Duration 
  FROM Students, Courses 
  WHERE Students.CourseID = Courses.CourseID 
  GROUP BY BookID

• BookID is used in the GROUP BY clause but is not present in the SELECT list, and it is also not a part of any aggregation (like COUNT(), SUM(), etc.).
• This violates the SQL standard rule and will result in an error in most RDBMS systems like MySQL, PostgreSQL, and SQL Server.

Additional Information

• Option 2 – It is a wrong query since is used in place of: This statement is unclear and grammatically incorrect; it doesn’t specify any real SQL issue.
• Option 3 – It is a wrong query as multiple tables are used in the SELECT clause: Not true. Joining multiple tables using WHERE is valid SQL.
• Option 4 – It is correctly formed query: ❌ Incorrect. The mismatch between SELECT and GROUP BY columns makes the query invalid.

Conclusion: The SQL query is incorrect because it uses GROUP BY on a column that is neither in the SELECT clause nor used in an aggregate function.