在BigQuery / SQL中展开数组值

Question

I was trying to unwind array values to different rows in BigQuery/ PSQL.

This is what I have right now ::

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

B                      array: {1,2,3}

C                      array: {4,5,6}

I want to convert this as shown below in BigQuery.

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

Answer 1

Using standard SQL (uncheck the "Use Legacy SQL" box under "Show Options") you can do:

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 |
+-------+-------+

Here the "comma" operator is equivalent to a cross join, which has the effect of flattening the repetition. As Pavan points out above, you can also accomplish this in legacy SQL using the FLATTEN operator, although the syntax is different.

Answer 2

If you are bound to BigQuery Legacy SQL - try below

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