MySQL Window Functions

Window Functions (MySQL 8.0+)

-- ROW_NUMBER
SELECT name, salary,
    ROW_NUMBER() OVER (ORDER BY salary DESC) AS rank_num
FROM employees;

-- RANK (ties get same rank, next rank skips)
SELECT name, dept, salary,
    RANK() OVER (PARTITION BY dept ORDER BY salary DESC) AS dept_rank
FROM employees;

-- DENSE_RANK (ties get same rank, no skipping)
SELECT name, DENSE_RANK() OVER (ORDER BY salary DESC) AS dense_rank
FROM employees;

-- LAG and LEAD
SELECT name, salary,
    LAG(salary, 1)  OVER (ORDER BY hire_date) AS prev_salary,
    LEAD(salary, 1) OVER (ORDER BY hire_date) AS next_salary
FROM employees;

-- Running total
SELECT name, amount,
    SUM(amount) OVER (ORDER BY created_at) AS running_total
FROM payments;