如何在 SQL [BQ] 中的語句中應用 ifnull 內部 case？

Question

如何在 case 中應用 ifnull 語句以避免在表中創建單獨的“field_1”列？ 輸入：

output：

SELECT ifnull(field_1, 'other'), count(*),
        case when field_1 = 'done'
        and market in ('usa', 'ca')
        and date < TIMESTAMP('2015-01-01')
        then
        'historical'
        else field_1 end as field_1
     FROM `tablename` 
     group by 1,3

Answer 1

您可以在條件語句中使用IS NULL ，如下所示：

SELECT 
  CASE  
    WHEN field_1 = 'done' AND market IN ('usa', 'ca') AND date < TIMESTAMP('2015-01-01') THEN 'historical'
    WHEN field_1 IS NULL THEN 'other'
    ELSE field_1
  END AS field_1
FROM your_table