RANK and DENSE_RANK difference in SQL

Introduction

RANK and DENSE_RANK help us order data by giving positions to rows based on values, but they handle ties differently.

When you want to list students by their scores and see their positions.

When you want to rank salespeople by sales and handle ties in ranking.

When you want to assign positions to players in a game leaderboard.

When you want to compare products by price and show their rank order.

Syntax

SQL

RANK() OVER (ORDER BY column_name [ASC|DESC])
DENSE_RANK() OVER (ORDER BY column_name [ASC|DESC])

Both functions assign ranks to rows ordered by the specified column.

RANK leaves gaps in ranking numbers when there are ties; DENSE_RANK does not.

Examples

Ranks players by score, skipping rank numbers if scores tie.

SQL

SELECT name, score, RANK() OVER (ORDER BY score DESC) AS rank FROM players;

Ranks players by score without skipping rank numbers for ties.

SQL

SELECT name, score, DENSE_RANK() OVER (ORDER BY score DESC) AS dense_rank FROM players;

Sample Program

This query shows how RANK and DENSE_RANK assign positions to players with tied scores.

SQL

WITH players AS (
  SELECT 'Alice' AS name, 100 AS score UNION ALL
  SELECT 'Bob', 90 UNION ALL
  SELECT 'Charlie', 90 UNION ALL
  SELECT 'David', 80
)
SELECT name, score,
       RANK() OVER (ORDER BY score DESC) AS rank,
       DENSE_RANK() OVER (ORDER BY score DESC) AS dense_rank
FROM players
ORDER BY score DESC;

Important Notes

RANK() can create gaps in ranking numbers after ties.

DENSE_RANK() always gives consecutive ranks without gaps.

Both functions require an ORDER BY clause inside the OVER() clause.

Summary

RANK and DENSE_RANK both assign ranks based on order.

RANK skips numbers after ties; DENSE_RANK does not.

Use them to understand positions when sorting data with possible ties.

Practice

1. What is the main difference between RANK() and DENSE_RANK() functions in SQL?

easy

A. DENSE_RANK() assigns random ranks, RANK() assigns sequential ranks.

B. RANK() skips rank numbers after ties, DENSE_RANK() does not skip numbers.

C. RANK() and DENSE_RANK() always return the same results.

D. DENSE_RANK() skips rank numbers after ties, RANK() does not skip numbers.

Solution

1. Step 1: Understand how RANK() works with ties

   RANK() assigns the same rank to tied rows but skips the next rank numbers accordingly. For example, if two rows tie for rank 1, the next rank will be 3.

2. Step 2: Understand how DENSE_RANK() works with ties

   DENSE_RANK() also assigns the same rank to tied rows but does not skip rank numbers. So after two rows tied at rank 1, the next rank will be 2.

3. Final Answer:

   RANK() skips rank numbers after ties, DENSE_RANK() does not skip numbers. -> Option B

4. Quick Check:

   Skipping ranks = RANK() [OK]

Hint: Remember: RANK skips numbers after ties, DENSE_RANK does not [OK]

Common Mistakes:

• Thinking both functions behave the same with ties
• Confusing which function skips rank numbers
• Assuming ranks are assigned randomly

2. Which of the following is the correct syntax to get the rank of employees ordered by salary using DENSE_RANK()?

easy

A. SELECT employee_id, RANK() BY salary FROM employees;

B. SELECT employee_id, DENSE_RANK(salary) FROM employees ORDER BY salary DESC;

C. SELECT employee_id, DENSE_RANK() OVER (ORDER BY salary DESC) AS rank FROM employees;

D. SELECT employee_id, DENSE_RANK() ORDER BY salary FROM employees;

Solution

1. Step 1: Identify correct DENSE_RANK() syntax

   The correct syntax uses DENSE_RANK() OVER (ORDER BY column) to rank rows based on a column.

2. Step 2: Check each option

   SELECT employee_id, DENSE_RANK() OVER (ORDER BY salary DESC) AS rank FROM employees; uses the correct window function syntax. Options A, B, and D have syntax errors or misuse the function.

3. Final Answer:

   SELECT employee_id, DENSE_RANK() OVER (ORDER BY salary DESC) AS rank FROM employees; -> Option C

4. Quick Check:

   Window function syntax = SELECT employee_id, DENSE_RANK() OVER (ORDER BY salary DESC) AS rank FROM employees; [OK]

Hint: Use OVER (ORDER BY ...) with ranking functions [OK]

Common Mistakes:

• Omitting OVER clause
• Passing column inside function parentheses
• Using wrong keywords like BY instead of ORDER BY

3. Given the table Scores with values:
Player | Score
Alice | 100
Bob | 90
Carol | 90
Dave | 80
What will be the output of this query?

SELECT Player, Score, RANK() OVER (ORDER BY Score DESC) AS Rank, DENSE_RANK() OVER (ORDER BY Score DESC) AS DenseRank FROM Scores;

medium

A. [{"Player":"Alice","Score":100,"Rank":1,"DenseRank":1},{"Player":"Bob","Score":90,"Rank":2,"DenseRank":2},{"Player":"Carol","Score":90,"Rank":2,"DenseRank":2},{"Player":"Dave","Score":80,"Rank":4,"DenseRank":3}]

B. [{"Player":"Alice","Score":100,"Rank":1,"DenseRank":1},{"Player":"Bob","Score":90,"Rank":3,"DenseRank":2},{"Player":"Carol","Score":90,"Rank":3,"DenseRank":2},{"Player":"Dave","Score":80,"Rank":4,"DenseRank":3}]

C. [{"Player":"Alice","Score":100,"Rank":1,"DenseRank":1},{"Player":"Bob","Score":90,"Rank":2,"DenseRank":3},{"Player":"Carol","Score":90,"Rank":2,"DenseRank":3},{"Player":"Dave","Score":80,"Rank":3,"DenseRank":4}]

D. [{"Player":"Alice","Score":100,"Rank":1,"DenseRank":1},{"Player":"Bob","Score":90,"Rank":2,"DenseRank":2},{"Player":"Carol","Score":90,"Rank":3,"DenseRank":2},{"Player":"Dave","Score":80,"Rank":4,"DenseRank":3}]

Solution

1. Step 1: Assign RANK() values

   Alice has highest score 100, rank 1. Bob and Carol tie at 90, both get rank 2. Because of tie at rank 2, next rank is 4 for Dave.

2. Step 2: Assign DENSE_RANK() values

   Alice is dense rank 1. Bob and Carol tie at 90, dense rank 2. Dave has next dense rank 3 (no skipping).

3. Final Answer:

   [{"Player":"Alice","Score":100,"Rank":1,"DenseRank":1},{"Player":"Bob","Score":90,"Rank":2,"DenseRank":2},{"Player":"Carol","Score":90,"Rank":2,"DenseRank":2},{"Player":"Dave","Score":80,"Rank":4,"DenseRank":3}] -> Option A

4. Quick Check:

   RANK skips numbers, DENSE_RANK does not [OK]

Hint: Check how ranks jump after ties for RANK vs DENSE_RANK [OK]

Common Mistakes:

• Assigning dense ranks with gaps
• Not skipping ranks in RANK after ties
• Mixing up rank numbers for tied rows

4. You wrote this query:

SELECT name, RANK() ORDER BY score DESC FROM players;

But it gives a syntax error. What is the problem?

medium

A. Missing OVER() clause after RANK() function.

B. ORDER BY cannot be used inside SELECT clause.

C. RANK() requires a parameter inside parentheses.

D. The table name is missing in the query.

Solution

1. Step 1: Check RANK() function usage

   RANK() is a window function and must be followed by OVER() clause specifying order.

2. Step 2: Identify missing OVER() clause

   The query uses RANK() without OVER(), causing syntax error.

3. Final Answer:

   Missing OVER() clause after RANK() function. -> Option A

4. Quick Check:

   Window functions need OVER() [OK]

Hint: Always add OVER() after window functions like RANK() [OK]

Common Mistakes:

• Forgetting OVER() clause
• Trying to put ORDER BY inside SELECT without OVER()
• Assuming RANK() takes parameters

5. You have a sales table:
Salesperson | SalesAmount
John | 500
Jane | 700
Joe | 700
Jill | 600
You want to assign ranks so that tied salespeople share the same rank and the next rank number is not skipped. Which query correctly achieves this?

hard

A. SELECT Salesperson, SalesAmount, RANK() OVER (ORDER BY SalesAmount DESC) AS Rank FROM sales;

B. SELECT Salesperson, SalesAmount, RANK() OVER (PARTITION BY SalesAmount ORDER BY SalesAmount DESC) AS Rank FROM sales;

C. SELECT Salesperson, SalesAmount, ROW_NUMBER() OVER (ORDER BY SalesAmount DESC) AS Rank FROM sales;

D. SELECT Salesperson, SalesAmount, DENSE_RANK() OVER (ORDER BY SalesAmount DESC) AS Rank FROM sales;

Solution

1. Step 1: Understand ranking requirements

   Tied salespeople should share the same rank, and the next rank number should not skip any numbers.

2. Step 2: Choose correct function

   DENSE_RANK() assigns same rank to ties and does not skip ranks. RANK() skips ranks after ties. ROW_NUMBER() never assigns same rank to ties. SELECT Salesperson, SalesAmount, RANK() OVER (PARTITION BY SalesAmount ORDER BY SalesAmount DESC) AS Rank FROM sales; misuses PARTITION BY.

3. Final Answer:

   SELECT Salesperson, SalesAmount, DENSE_RANK() OVER (ORDER BY SalesAmount DESC) AS Rank FROM sales; -> Option D

4. Quick Check:

   DENSE_RANK() for no skipped ranks after ties [OK]

Hint: Use DENSE_RANK() to avoid skipping ranks after ties [OK]

Common Mistakes:

• Using RANK() when no skipping is wanted
• Using ROW_NUMBER() which never ties
• Incorrect use of PARTITION BY in ranking