在BigQuery / SQL中展开数组值

Question

我试图将数组值展开为BigQuery / PSQL中的不同行。

这就是我现在拥有的::

Col_1                    col_2
A                      array: {1,2,3,4,5}

B                      array: {1,2,3}

C                      array: {4,5,6}

我想按如下BigQuery所示进行转换。

A          1
A          2
A          3
A          4
A          5
B          1
B          2
B          3
C          4
C          5
C          6

Answer 1

使用标准SQL （取消选中“显示选项”下的“使用旧版SQL”框），您可以执行以下操作：

WITH MyTable AS (
  SELECT 'A' AS Col_1, [1, 2, 3, 4, 5] AS col_2
  UNION ALL SELECT 'B', [1, 2, 3]
  UNION ALL SELECT 'C', [4, 5, 6])
SELECT Col_1, col_2 FROM MyTable t, t.col_2;
+-------+-------+
| Col_1 | col_2 |
+-------+-------+
| A     |     1 |
| A     |     2 |
| A     |     3 |
| A     |     4 |
| A     |     5 |
| B     |     1 |
| B     |     2 |
| B     |     3 |
| C     |     4 |
| C     |     5 |
| C     |     6 |
+-------+-------+

此处的“逗号”运算符等效于交叉连接，具有平整重复的效果。 正如Pavan指出的那样，尽管语法不同，您也可以使用FLATTEN运算符在旧版SQL中完成此操作。

Answer 2

如果您必须使用BigQuery旧版SQL，请尝试以下操作

SELECT col_1, SPLIT(REPLACE(REPLACE(SPLIT(col_2, ':'), '{', ''), '}', ''), ',') AS elem 
FROM
  (SELECT 'A' AS col_1, 'array: {1,2,3,4,5}' AS col_2),
  (SELECT 'B' AS col_1, 'array: {1,2,3}' AS col_2),
  (SELECT 'C' AS col_1, 'array: {4,5,6}' AS col_2)
HAVING elem <> 'array'  

col_1   elem     
A       1    
A       2    
A       3    
A       4    
A       5    
B       1    
B       2    
B       3    
C       4    
C       5    
C       6