I have a certain query which is working fine. The problem is that a part of that query is a string that needs to be read from a file. Query for each string produces 6 outputs. I need a union of all the results for that file such that the end result is a table fo 6x number of strings. I can read the file using Python.
I've already tried using parameterised queries. Each of them only return the 6 rows based on the string.
Most of my Python code is based on BigQuery's documentation here .
query = """
SELECT pet_id, age, name
FROM `myproject.mydataset.mytable`
WHERE name = @name
AND species = @species;
"""
query_params = [
bigquery.ScalarQueryParameter('name', 'STRING', 'Max'),
bigquery.ScalarQueryParameter('species', 'INT64', 'Dog'),
bigquery.ScalarQueryParameter('name', 'STRING', 'Alfred'),
bigquery.ScalarQueryParameter('species', 'INT64', 'Cat')
]
job_config = bigquery.QueryJobConfig()
job_config.query_parameters = query_params
query_job = client.query(
query,
# Location must match that of the dataset(s) referenced in the query.
location='US',
job_config=job_config) # API request - starts the query
# Print the results
for row in query_job:
print('{}: \t{}'.format(row.word, row.word_count))
How can I get a UNION ALL of many of these query results?
The output should look like
pet_id | age | name
___________________
1 | 5 | Max
2 | 8 | Alfred
Please look at below example using public data (you can run the query as well)
#standardSQL
SELECT *
FROM `bigquery-public-data.baseball.schedules`
WHERE (year, duration_minutes) IN UNNEST([(2016, 187), (2016, 165), (2016, 189)])
The key here is for you to provide an array of value that you want to filter the table with, and use IN UNNEST(array_of_values) to do the job, ideally like below:
query = """
SELECT pet_id, age, name
FROM `myproject.mydataset.mytable`
WHERE (name, species) IN UNNEST(@filter_array);
"""
It is a bit unfortunate that BigQuery Python API doesn't let you specify array< struct<string, int64> >
as query parameter. So you may have to do:
query = """
SELECT pet_id, age, name
FROM `myproject.mydataset.mytable`
WHERE concat(name, "_", species) IN UNNEST(@filter_array);
"""
array_of_pre_concatenated_name_and_species = ['Max_Dog', 'Alfred_Cat']
query_params = [
bigquery.ArrayQueryParameter('filter_array', 'STRING', array_of_pre_concatenated_name_and_species),
]
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