如何在bigquery中使用基于另一个列值的列值

SELECT
  user_id,
  age,
  CASE
    WHEN age < 18 THEN 'Child'
    WHEN age BETWEEN 18 AND 64 THEN 'Adult'
    ELSE 'Senior'
  END AS age_group
FROM
  `project.dataset.users`

SELECT
  product_id,
  sale_date,
  sale_amount,
  SUM(sale_amount) OVER (PARTITION BY product_id ORDER BY sale_date) AS cumulative_sales
FROM
  `project.dataset.sales`

SELECT
  o.order_id,
  o.user_id,
  o.order_amount,
  u.total_order_amount
FROM
  `project.dataset.orders` o
JOIN (
  SELECT
    user_id,
    SUM(order_amount) AS total_order_amount
  FROM
    `project.dataset.orders`
  GROUP BY
    user_id
) u
ON
  o.user_id = u.user_id

SELECT
  product_id,
  price,
  IF(price < 50, 'Cheap', 'Expensive') AS price_category
FROM
  `project.dataset.products`

SELECT
  user_id,
  nickname,
  username,
  COALESCE(nickname, username) AS display_name
FROM
  `project.dataset.users`