Question

我不知道如何做到这一点，并查看了if函数，但似乎无法让它工作。在伪代码中

data(if (q1, truequery, falsequery)) select ... from `data`

基本上我想要做的是如果查询返回结果，运行一个查询，如果不运行另一个查询。任何帮助/领导都会很棒，谢谢！

Answer 1

尝试下面的BigQuery Standard SQL示例

#standardSQL
WITH tableA AS (
  SELECT 1 AS x
),
tableB AS (
  SELECT 2 AS x
),
truequery AS (
  SELECT * FROM tableA WHERE x = 1
),
falsequery AS (
  SELECT * FROM tableB
)
SELECT * FROM truequery UNION ALL 
SELECT * FROM falsequery WHERE (SELECT COUNT(1) FROM truequery) = 0

希望这能给你带来好主意请注意：两个查询的输出模式应该相同

我可以在另一个WITH allTables AS（...）中执行所有这些，然后对其运行查询吗？

#standardSQL
WITH tableA AS (
  SELECT 1 AS x
),
tableB AS (
  SELECT 2 AS x
),
truequery AS (
  SELECT * FROM tableA WHERE x = 777
),
falsequery AS (
  SELECT * FROM tableB
),
allTables AS (
  SELECT * FROM truequery UNION ALL 
  SELECT * FROM falsequery WHERE (SELECT COUNT(1) FROM truequery) = 0
)
SELECT * FROM allTables

BigQuery根据结果运行不同的查询？

1 个答案: