22.1. SQL Part 4 - Subqueries, UNION, INTERSECT, EXCEPT¶
Read the following articles:
22.1.1. Subqueries¶
22.1.2. UNION
, INTERSECT
, EXCEPT
¶
22.1.4. Check Your Understanding¶
Question
Every statement that uses a subquery can be re-written as a JOIN
.
True
False
Question
A subquery cannot use ORDER BY
, but the main query can.
True
False
Question
Match the operator to the result set:
|
Combined rows from both queries. |
|
Only keeps rows in common with both queries. |
|
Keeps rows from left query that aren’t in common with right query. |
Question
UNION
combines columns and JOINS
combine rows.
True
False
Question
What is the difference between a correlated subquery and a nested subquery?