How to unnest and pivot two columns in BigQuery

Question

Say I have a BQ table containing the following information

id	test.name	test.score
1	a	5
	b	7
2	a	8
	c	3

Where test is nested. How would I pivot test into the following table?

id	a	b	c
1	5	7
2	8		3

I cannot pivot test directly, as I get the following error message at pivot(test): Table-valued function not found. Previous questions (1, 2) don't deal with nested columns or are outdated.

The following query looks like a useful first step:

select a.id, t
from `table` as a,
unnest(test) as t

However, this just provides me with:

id	test.name	test.score
1	a	5
1	b	7
2	a	8
2	c	3

Answer 1

Below is generic/dynamic way to handle your case

EXECUTE IMMEDIATE (
  SELECT """
  SELECT id, """ || 
    STRING_AGG("""MAX(IF(name = '""" || name || """', score, NULL)) AS """ || name, ', ') 
  || """
  FROM `project.dataset.table` t, t.test
  GROUP BY id
  """
  FROM (
    SELECT DISTINCT name
    FROM `project.dataset.table` t, t.test
    ORDER BY name
  )
);  

If to apply to sample data from your question - output is

Row     id      a       b       c    
1       1       5       7       null     
2       2       8       null    3