Quiz for INNER JOIN

Q1: What does an INNER JOIN return?

A. All records from both tables B. Only unmatched rows C. Only matched rows D. None of the above

Q2: Which SQL JOIN returns only the matching rows from both tables?

A. LEFT JOIN B. RIGHT JOIN C. INNER JOIN D. FULL OUTER JOIN

Q3: Which clause is used to specify the matching condition in INNER JOIN?

A. ON B. USING C. WHERE D. GROUP BY

Q4: Which of the following is a correct INNER JOIN syntax?

A. SELECT * FROM A JOIN B; B. SELECT * FROM A INNER JOIN B ON A.id = B.id; C. SELECT * INNER JOIN A, B; D. JOIN A AND B ON A.id = B.id;

Q5: What happens if no matching rows are found in INNER JOIN?

A. NULL rows are returned B. All rows from left table are returned C. No rows are returned D. All rows from right table are returned

Q6: What is required for an INNER JOIN to work properly?

A. Common column names B. A subquery C. Matching values in joined columns D. Same number of rows

Q7: Can INNER JOIN be used with more than two tables?

A. Yes B. No C. Only with self join D. Only in subqueries

Q8: Which operator is most commonly used in INNER JOIN conditions?

A. = B. <> C. LIKE D. IN

Q9: What is the default join type when only JOIN is written in SQL?

A. LEFT JOIN B. RIGHT JOIN C. FULL JOIN D. INNER JOIN

Q10: Which SQL clause is used to filter results after an INNER JOIN?

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

Q11: What is the result of joining two tables with no common matching values?

A. All rows from both tables B. All rows from left table C. All rows from right table D. No rows returned

Q12: How does INNER JOIN differ from LEFT JOIN?

A. It includes all left rows B. It excludes non-matching rows C. It includes NULLs from right D. It always uses USING clause

Q13: What keyword follows INNER JOIN to define the join condition?

A. WITH B. FROM C. ON D. HAVING

Q14: Which is true about INNER JOIN and CROSS JOIN?

A. Both return same results B. INNER JOIN needs a condition C. CROSS JOIN excludes duplicates D. CROSS JOIN returns matching records

Q15: Can INNER JOIN return duplicate rows?

A. Yes, if data matches multiple times B. No, it removes duplicates C. Only with GROUP BY D. Only with DISTINCT

Q16: In INNER JOIN, what happens if column names are same in both tables?

A. Error occurs B. You must use table aliases or qualify names C. Only first table is used D. Query fails

Q17: Which of these is a valid INNER JOIN using aliases?

A. SELECT * FROM emp e JOIN dept d ON emp.deptno = d.deptno; B. SELECT * FROM emp e INNER JOIN dept d ON e.deptno = d.deptno; C. SELECT e.*, d.* FROM emp JOIN dept; D. SELECT FROM emp JOIN dept;

Q18: What is a common use case of INNER JOIN?

A. Deleting rows B. Grouping rows C. Fetching related data from two tables D. Sorting records

Q19: What does the following query do: SELECT * FROM A INNER JOIN B ON A.id = B.id;

A. Returns all rows from A B. Returns rows with matching id from A and B C. Returns unmatched rows D. Deletes unmatched data

Q20: Is it mandatory to use INNER keyword for INNER JOIN?

A. Yes B. No C. Only in MySQL D. Only with WHERE clause

Q21: Which join type returns the most limited result set if conditions are strict?

A. FULL JOIN B. LEFT JOIN C. RIGHT JOIN D. INNER JOIN