PLEASE answer these two SQL question with a short answer. Thank you

QUESTION 20 What can the expression first_name || || last_name be replaced with in the ORDER BY clause (mentioned only the term to be replaced with in your answer, do not mention the whole ORDER BY clause)? SELECT student_id, first_name || ' || last_name AS full_name FROM students WHERE student_id >= 1000 ORDER BY first_name 11 " || last_name; QUESTION 22 Write an equivalent single SQL statement which can replace the below 2 SQL statements: DELETE FROM countries; COMMIT