Quiz for INTERSECT

Q1: What does the INTERSECT operator return?

A. All rows from the first query B. All unique rows from both queries C. Rows common to both queries D. All duplicate rows only

Q2: What does the INTERSECT operator do in SQL?

A. Combines all rows B. Removes duplicate rows C. Returns common rows from two queries D. Returns unmatched rows

Q3: Which clause must be present in both queries when using INTERSECT?

A. GROUP BY B. ORDER BY C. WHERE D. SELECT

Q4: What happens if the number of columns does not match in INTERSECT?

A. Returns NULLs B. Query still works C. Error is thrown D. Partial result

Q5: INTERSECT operator automatically removes:

A. All rows B. Duplicate rows C. Nulls D. Sorted data

Q6: Which operator is most similar to INTERSECT in its result behavior?

A. UNION B. JOIN C. MINUS D. INNER JOIN

Q7: What is the result of INTERSECT between a full table and an empty table?

A. All rows B. Some rows C. No rows D. NULL

Q8: Can INTERSECT be used with different data types in the columns?

A. Yes B. No C. Sometimes D. Only with conversion

Q9: Which SQL databases do NOT support INTERSECT by default?

A. MySQL B. PostgreSQL C. Oracle D. SQL Server

Q10: To ensure deterministic output from INTERSECT, you should use:

A. JOINs B. ORDER BY C. GROUP BY D. HAVING

Q11: What keyword ensures that INTERSECT is case-insensitive?

A. ILIKE B. COLLATE C. BINARY D. There is none

Q12: Can INTERSECT be used between a SELECT with WHERE and one without?

A. Yes B. No C. Only with aliases D. Only with subqueries

Q13: Which clause can appear after an INTERSECT statement?

A. LIMIT B. JOIN C. WHERE D. SET

Q14: What does INTERSECT do when two rows are identical but differ in case?

A. Returns both B. Returns none C. Depends on collation D. Duplicates both

Q15: How many queries are required for an INTERSECT operation?

A. 1 B. 2 C. At least 3 D. Any number

Q16: What happens when both SELECTs in INTERSECT return NULL values?

A. NULLs are ignored B. NULLs are matched C. Only one NULL shown D. All NULLs shown

Q17: What is a major difference between INNER JOIN and INTERSECT?

A. Join creates new columns B. INTERSECT filters rows only C. No difference D. INNER JOIN returns fewer rows

Q18: Which clause cannot be used inside an INTERSECT component query?

A. ORDER BY B. WHERE C. GROUP BY D. HAVING

Q19: What result is returned if INTERSECT has completely distinct rows in both queries?

A. All rows B. Some rows C. No rows D. NULL only

Q20: What clause helps optimize performance with INTERSECT?

A. JOIN B. GROUP BY C. INDEX D. UNION

Q21: Which is a valid example of using INTERSECT?

A. SELECT * FROM A INTERSECT SELECT * FROM B; B. SELECT A INTERSECT B; C. SELECT FROM A INTERSECT B; D. SELECT A AND B;