Mastering IS NULL Queries in GCP BigQuery

n Google Cloud BigQuery, you can retrieve rows where a field contains NULL values by using the IS NULL condition in your SQL query. Here's how you can achieve this:

Basic Query for NULL Values

SELECT *
FROM `project_id.dataset_id.table_name`
WHERE field_name IS NULL;

Additional Use Cases

1. Retrieve Rows Where a Field is NOT NULL

To find rows where the field is not NULL, use the IS NOT NULL condition:

SELECT *
FROM `project_id.dataset_id.table_name`
WHERE field_name IS NOT NULL;

2. Count Rows with NULL Values

To count how many rows have NULL values in a field:

SELECT COUNT(*)
FROM `project_id.dataset_id.table_name`
WHERE field_name IS NULL;

3. Handle Multiple Fields

If you want to check for NULL in multiple fields:

SELECT *
FROM `project_id.dataset_id.table_name`
WHERE field1 IS NULL OR field2 IS NULL;

4. Aggregate and Ignore NULL Values

Functions like SUM, AVG, COUNT, etc., automatically ignore NULL values unless specified otherwise.