根据查询中的旧列创建新列-BQ

Question

我的下表如下：

id  | gained  | init
-----------------------
1da |   56    |  TRUE
1da |   56    |  FALSE
e4f |   23    |  TRUE
few |   23    |  TRUE

新列new_gained应通过查询派生，逻辑应为： CASE WHEN init is true THEN 0 ELSE gained END

我想要的查询结果：

id  | gained  | init  | new_gained
-----------------------------------
1da |   56    |  TRUE |     0
1da |   56    | FALSE |     56
e4f |   23    |  TRUE |     0
few |   23    |  TRUE |     0

Answer 1

不确定问题的根源是什么-无论如何-以下是您的问题

#standardSQL
WITH `project.dataset.table` AS (
  SELECT '1da' id, 56 gained, TRUE init UNION ALL
  SELECT '1da', 56, FALSE UNION ALL
  SELECT 'e4f', 23, TRUE UNION ALL
  SELECT 'few', 23, TRUE 
)
SELECT *, 
  CASE WHEN init THEN 0 ELSE gained END AS new_gained 
FROM `project.dataset.table`  

另一个选择是

#standardSQL
SELECT *, 
  IF(init, 0, gained) AS new_gained 
FROM `project.dataset.table`