Question

按照以某种方式编辑的值进行分组并重命名相同的值时，更新的值（而不是原始值）似乎会将select语句级联起来。这是预期的行为吗？

SELECT
  a+1 AS a,
  FIRST(a) AS b
FROM (SELECT 1 AS a),
     (SELECT 2 AS a)
GROUP BY
  a    

-- a | b
-- -----
-- 2 | 2
-- 3 | 3

VS

SELECT
  a+1 AS a_incremented,
  FIRST(a) AS b
FROM (SELECT 1 AS a),
     (SELECT 2 AS a)
GROUP BY
  a_incremented

-- a_incremented | b     
--       2       | 1
--       3       | 2

Answer 1

以下示例提供了对此

的更多见解

SELECT
  a + 1 AS a,
  FIRST(a) AS b,
  FIRST(a + 0) AS b0,
  FIRST(a + 1) AS b1,
  FIRST(a + 2) AS b2
FROM (SELECT 1 AS a),
     (SELECT 2 AS a)
GROUP BY
  a   

a   b   b0  b1  b2   
2   2   1   2   3    
3   3   2   3   4

我为自己找到了通过这种混乱的规则如果我在任何表达式中使用重载字段/别名（在本例中为a）（例如b0，b1，b2），它（BigQuery）使用原始字段
如果我自己使用那个重载的字段/别名（对于b），它使用别名

Alias＆＃39;应该在分组时级联？

1 个答案: