1. What is INNER JOIN ? Junior A. returns all rows from both tables, matching them where possible B. returns only rows with a matching key in both tables C. joins a table to itself, e.g. to relate employees to their managers D. returns the Cartesian product — every row of one table paired with every row of the other
2. Which term means: "returns only rows with a matching key in both tables"? Junior A. CROSS JOIN B. INNER JOIN C. LEFT JOIN D. SELF JOIN
3. Which statement is correct? Junior A. INNER JOIN — joins a table to itself, e.g. to relate employees to their managers B. INNER JOIN — returns only rows with a matching key in both tables C. INNER JOIN — ON specifies an arbitrary join condition; USING joins on identically named columns D. INNER JOIN — returns all rows from both tables, matching them where possible
4. What is LEFT JOIN ? Junior A. ON specifies an arbitrary join condition; USING joins on identically named columns B. returns only rows with a matching key in both tables C. joins a table to itself, e.g. to relate employees to their managers D. returns all rows from the left table plus matches from the right, NULLs where none match
5. Which term means: "returns all rows from the left table plus matches from the right, NULLs where none match"? Junior A. LEFT JOIN B. SELF JOIN C. FULL OUTER JOIN D. CROSS JOIN
6. Which statement is correct? Junior A. LEFT JOIN — returns the Cartesian product — every row of one table paired with every row of the other B. LEFT JOIN — ON specifies an arbitrary join condition; USING joins on identically named columns C. LEFT JOIN — returns only rows with a matching key in both tables D. LEFT JOIN — returns all rows from the left table plus matches from the right, NULLs where none match
7. What is FULL OUTER JOIN ? Mid A. returns all rows from the left table plus matches from the right, NULLs where none match B. returns only rows with a matching key in both tables C. ON specifies an arbitrary join condition; USING joins on identically named columns D. returns all rows from both tables, matching them where possible
8. Which term means: "returns all rows from both tables, matching them where possible"? Mid A. CROSS JOIN B. ON vs USING C. SELF JOIN D. FULL OUTER JOIN
9. Which statement is correct? Mid A. FULL OUTER JOIN — returns the Cartesian product — every row of one table paired with every row of the other B. FULL OUTER JOIN — returns only rows with a matching key in both tables C. FULL OUTER JOIN — returns all rows from both tables, matching them where possible D. FULL OUTER JOIN — joins a table to itself, e.g. to relate employees to their managers
10. What is CROSS JOIN ? Mid A. joins a table to itself, e.g. to relate employees to their managers B. ON specifies an arbitrary join condition; USING joins on identically named columns C. returns only rows with a matching key in both tables D. returns the Cartesian product — every row of one table paired with every row of the other
11. Which term means: "returns the Cartesian product — every row of one table paired with every row of the other"? Mid A. CROSS JOIN B. FULL OUTER JOIN C. SELF JOIN D. INNER JOIN
12. Which statement is correct? Mid A. CROSS JOIN — returns the Cartesian product — every row of one table paired with every row of the other B. CROSS JOIN — returns all rows from both tables, matching them where possible C. CROSS JOIN — joins a table to itself, e.g. to relate employees to their managers D. CROSS JOIN — returns only rows with a matching key in both tables
13. What is SELF JOIN ? Mid A. joins a table to itself, e.g. to relate employees to their managers B. returns only rows with a matching key in both tables C. returns all rows from both tables, matching them where possible D. returns the Cartesian product — every row of one table paired with every row of the other
14. Which term means: "joins a table to itself, e.g. to relate employees to their managers"? Mid A. SELF JOIN B. FULL OUTER JOIN C. INNER JOIN D. CROSS JOIN
15. Which statement is correct? Mid A. SELF JOIN — returns all rows from both tables, matching them where possible B. SELF JOIN — joins a table to itself, e.g. to relate employees to their managers C. SELF JOIN — ON specifies an arbitrary join condition; USING joins on identically named columns D. SELF JOIN — returns all rows from the left table plus matches from the right, NULLs where none match
16. What is ON vs USING ? Mid A. ON specifies an arbitrary join condition; USING joins on identically named columns B. returns all rows from the left table plus matches from the right, NULLs where none match C. returns all rows from both tables, matching them where possible D. returns the Cartesian product — every row of one table paired with every row of the other
17. Which term means: "ON specifies an arbitrary join condition; USING joins on identically named columns"? Mid A. CROSS JOIN B. ON vs USING C. FULL OUTER JOIN D. LEFT JOIN
18. Which statement is correct? Mid A. ON vs USING — returns the Cartesian product — every row of one table paired with every row of the other B. ON vs USING — ON specifies an arbitrary join condition; USING joins on identically named columns C. ON vs USING — returns all rows from the left table plus matches from the right, NULLs where none match D. ON vs USING — returns all rows from both tables, matching them where possible