In BigQuery, the NOT NULL constraint is a key tool when working with databases. When creating a table, you can specify if a specific column should not be null by adding the NOT NULL to the column declaration.
You can verify this constraint on an existing table by checking the column (field) MODE. The MODE can have three values:
- NULLABLE: The default value if nothing is set.
- REQUIRED: Set if NOT NULL is declared for the column.
- REPEATED: Used for ARRAYS.
If an attempt is made to insert or update data that violates this constraint, the operation will fail. Therefore, correctly setting the MODE for your field is crucial to ensure the data inserted or updated in a table meets your expectations.
