Which two statements are true regarding subqueries? (Choose three.)
A.
The ORDER BY clause can be used in the subquery.
B.
A subquery can be used in the FROM clause of a SELECT statement.
C.
If the subquery returns NULL, the main query may still return result rows.
D.
A subquery can be placed in a WHERE clause, GROUP BY clause, or a HAVING clause.
E.
Logical operators, such as AND, OR and NOT, cannot be used in the WHERE clause of a
subquery.
1) Why question say “Which two statements” and there are 3 answers?
2) There are only two answers in another sources: A and B. I think they are wrong, but…
A and B seems to be the correct answer.
if use NOT IN, for example, for INNER query with possible NULL values, then USE NVL function in inner Select to return values ==> + answer C