BigQuery select expect double nested column - google-bigquery

Question

I am trying to remove a column from a BigQuery table and I've followed the instructions as stated here:
https://cloud.google.com/bigquery/docs/manually-changing-schemas#deleting_a_column_from_a_table_schema
This did not work directly as the column I'm trying to remove is nested twice in a struct. The following SO questions are relevant but none of them solve this exact case.
Single nested field:
BigQuery select * except nested column
Double nested field (solution has all fields in the schema enumerated, which is not useful for me as my schema is huge):
BigQuery: select * replace from multiple nested column
I've tried adapting the above solutions and I think I'm close but can't quite get it to work.
This one will remove the field, but returns only the nested field, not the whole table (for the examples I want to remove a.b.field_name. See the example schema at the end):
SELECT AS STRUCT * EXCEPT(a), a.* REPLACE (
(SELECT AS STRUCT a.b.* EXCEPT (field_name)) AS b
)
FROM `table`
This next attempt gives me an error: Scalar subquery produced more than one element:
WITH a_tmp AS (
SELECT AS STRUCT a.* REPLACE (
(SELECT AS STRUCT a.b.* EXCEPT (field_name)) AS b
)
FROM `table`
)
SELECT * REPLACE (
(SELECT AS STRUCT a.* FROM a_tmp) AS a
)
FROM `table`
Is there a generalised way to solve this? Or am I forced to use the enumerated solution in the 2nd link?
Example Schema:
[
{
"name": "a",
"type": "RECORD",
"fields": [
{
"name": "b",
"type": "RECORD"
"fields": [
{
"name": "field_name",
"type": "STRING"
},
{
"name": "other_field_name".
"type": "STRING"
}
]
},
]
}
]
I would like the final schema to be the same but without field_name.

Answer 1

Below is for BigQuery Standard SQL
#standardSQL
SELECT * REPLACE(
(SELECT AS STRUCT(SELECT AS STRUCT a.b.* EXCEPT (field_name)) b)
AS a)
FROM `project.dataset.table`
you can test, play with it using dummy data as below
#standardSQL
WITH `project.dataset.table` AS (
SELECT STRUCT<b STRUCT<field_name STRING, other_field_name STRING>>(STRUCT('1', '2')) a
)
SELECT * REPLACE(
(SELECT AS STRUCT(SELECT AS STRUCT a.b.* EXCEPT (field_name)) b)
AS a)
FROM `project.dataset.table`