mysql有dense rank

CREATE TABLE sales (
    id INT PRIMARY KEY,
    salesperson VARCHAR(50),
    amount DECIMAL(10, 2)
);

INSERT INTO sales (id, salesperson, amount) VALUES
(1, 'Alice', 1000),
(2, 'Bob', 1500),
(3, 'Charlie', 1500),
(4, 'David', 2000),
(5, 'Eve', 2000);

SELECT 
    salesperson, 
    amount, 
    DENSE_RANK() OVER (ORDER BY amount DESC) AS rank
FROM sales;

salesperson | amount   | rank
------------|----------|------
David       | 2000.00  | 1
Eve         | 2000.00  | 1
Bob         | 1500.00  | 2
Charlie     | 1500.00  | 2
Alice       | 1000.00  | 3

DENSE_RANK() OVER (ORDER BY amount DESC)

DENSE_RANK() OVER (PARTITION BY department ORDER BY amount DESC)