1Z0-071 Cheat Sheet 2026

The 30 highest-yield 1Z0-071 facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is a foreign key in a relational database? → A key that is used to link two tables together by establishing a relationship.
2. Why is UNION generally slower in performance compared to UNION ALL? → UNION requires an additional sort and deduplication step to eliminate duplicate rows
3. Which clause is used to filter the results of a GROUP BY query? → HAVING
4. What does the COUNT(*) function return? → Total number of rows including NULLs
5. What is the result of a CROSS JOIN between a table with 4 rows and a table with 3 rows? → 12 rows
6. Which SQL clause is used to filter rows returned by a query based on a specified condition? → WHERE
7. Which clause in a JOIN allows you to specify a single common column name without a table prefix? → USING
8. In the EMPLOYEES table, the MANAGER_ID references EMPLOYEE_ID in the same table. What type of join retrieves each employee and their manager's name? → Self-join
9. Which set operator returns all rows from both queries, including duplicate rows? → UNION ALL
10. Which set operator returns only the rows that appear in both result sets? → INTERSECT
11. What happens in an INNER JOIN when no rows satisfy the join condition? → An empty result set is returned
12. Which aggregate function is used to find the average salary per department? → AVG()
13. Which DDL command is used to remove a column from an existing table? → ALTER TABLE ... DROP COLUMN
14. Which of the following correctly describes how set operators handle NULL values when comparing rows? → Set operators treat two NULL values as equal when determining row matches
15. What does a CHECK constraint do? → Verifies that column values satisfy a specific condition
16. Which two are SQL features? → providing database transaction control
17. When combining two SELECT statements with a set operator, which of the following is a mandatory requirement? → Both SELECT statements must return the same number of columns
18. What is a NATURAL JOIN in Oracle SQL? → A join that uses all columns with the same name in both tables
19. What type of join returns rows from both tables regardless of whether a match exists? → FULL OUTER JOIN
20. Which keyword must follow a table name when performing an ANSI-style FULL OUTER JOIN? → FULL OUTER JOIN
21. Which SQL syntax represents an ANSI-standard INNER JOIN? → SELECT * FROM a JOIN b ON a.id = b.id
22. Which function returns the highest value in a set of values? → MAX()
23. Which of the following queries correctly places the ORDER BY clause when using set operators? → SELECT id FROM emp UNION SELECT id FROM dept ORDER BY id;
24. In a compound query using set operators, an ORDER BY clause can reference output columns using which methods? → Column aliases from the first SELECT or position numbers
25. Which Oracle data type stores large amounts of character data beyond 4000 bytes? → CLOB
26. A query uses GROUP BY department_id. Which column can appear in the SELECT list WITHOUT being inside an aggregate function? → department_id
27. A subquery that returns more than one column is called a: → Multiple-column subquery
28. An EMPLOYEES table has 10 rows; a DEPARTMENTS table has 5 rows. A CROSS JOIN returns how many rows? → 50
29. Which of the following is NOT a valid set operator in Oracle SQL? → INTERSECT ALL
30. What is the result of using COUNT(column_name) when some rows have NULL in that column? → It counts only non-NULL rows