How to fix 22016: invalid_argument_for_nth_value_function in PostgreSQL

NTH_VALUE(expression, n) OVER (
  [PARTITION BY ...]
  ORDER BY ...
  [frame_clause]
)

-- Wrong: position is zero
SELECT NTH_VALUE(salary, 0) OVER (ORDER BY salary) FROM employees;

-- Correct: position is a positive integer
SELECT NTH_VALUE(salary, 2) OVER (ORDER BY salary) FROM employees;

-- If using a calculated position
SELECT NTH_VALUE(column_name, CAST(position_value AS INTEGER)) 
OVER (ORDER BY other_column) 
FROM table_name;

-- Or use ::integer shorthand
SELECT NTH_VALUE(column_name, position_value::integer) 
OVER (ORDER BY other_column) 
FROM table_name;

SELECT 
  employee_id,
  salary,
  NTH_VALUE(salary, 2) OVER (
    ORDER BY salary DESC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
  ) AS second_highest_salary
FROM employees;

SELECT 
  product_id,
  price,
  CASE 
    WHEN position_value > 0 
    THEN NTH_VALUE(price, position_value::integer) OVER (ORDER BY price)
    ELSE NULL
  END AS nth_price
FROM products;