Given the following query:

Which of the following is true about the dept_rank column?

Question

Given the following query:

Which of the following is true about the dept_rank column?

BlackTom AI · Accepted Answer

RANK() assigns the same rank to tied rows and leaves gaps in the subsequent ranks.

1) Relevant knowledge points and concepts
- Window functions compute values across rows related to the current row; RANK() is one such function.
- RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) ranks employees within each department by salary, highest salary getting rank 1.
- Behavior on ties: RANK() gives equal ranks to tied values and skips subsequent rank numbers (creates gaps). Compare: DENSE_RANK() does not skip numbers; ROW_NUMBER() always gives unique sequential numbers.

2) Complete reasoning process step by step
- Partition the table by department_id so ranking restarts per department.
- Order rows within each partition by salary DESC so highest salary receives lowest numeric rank (1).
- For each row, determine how many rows have a strictly higher salary in the same partition; rank = 1 + number_of_rows_with_higher_salary. Rows with equal salary have the same count of higher rows, thus same rank.

3) Intermediate step example (explicit calculation)
Example salaries in one department: [90000, 90000, 80000, 70000]
- For 90000 (first): number_higher = 0 → rank = 1
- For 90000 (second): number_higher = 0 → rank = 1 (tie)
- For 80000: number_higher = 2 → rank = 3
- For 70000: number_higher = 3 → rank = 4

4) Why the correct answer is correct
The third option, "If two employees tie in salary, the next rank will be skipped," exactly describes RANK()’s behavior: ties share the same rank and the following rank reflects the position as if those tied rows occupied consecutive ranks, producing a gap (e.g., 1,1,3).

5) Why the other options are incorrect
- "RANK() returns the number of rows in each partition.": False — RANK() returns position-based ranks, not partition counts.
- "Rank is assigned without skipping numbers in case of ties.": False — that describes DENSE_RANK(), not RANK().
- "Employees in the same department with the same salary will get different ranks.": False — RANK() gives equal ranks to tied values; ROW_NUMBER() would give different ranks.

6) Conclusion
Therefore, the correct statement is: "If two employees tie in salary, the next rank will be skipped." This matches the provided answer.

Given the following query: Which of the following is true about the dept_rank column?单项选择题

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