A code example for how to write BigQuery SQL to export a table to Google Cloud Storage in csv and parquet file formats.
Parquet

-- Export a table in BigQuery to Google Cloud Storage in parquet file format
EXPORT DATA OPTIONS(
uri='gs://a_google_cloud_storage_bucket/a_folder/prefix_for_the_saved_file-*.parquet',
format='PARQUET',
overwrite=true
) AS
SELECT
*
FROM a-project.a-dataset.table_to_export_to_gcs_in_parquet_format;
CSV

-- Export a table in BigQuery to Google Cloud Storage in csv file format
EXPORT DATA OPTIONS(
uri='gs://a_google_cloud_storage_bucket/a_folder/prefix_for_the_saved_file-*.csv',
format='CSV',
overwrite=true,
header=true,
field_delimiter=','
) AS
SELECT
*
FROM a-project.a-dataset.table_to_export_to_gcs_in_csv_format;