title: For Bigquery table schemas, how do I change a column's mode from NULLABLE to REQUIRED?
body: <p>I have a table in BigQuery and want to change the mode of a column from NULLABLE to REQUIRED.</p>
  <p>According to the Google documentation for modifying BigQuery table schemas the only way to do this goes as follows: &quot;You can manually change a column's mode by exporting your table data to Cloud Storage, and then loading the data into a new table with a schema definition that specifies the correct mode for the column. You can also use the load job to overwrite the existing table.&quot; (<a href="https://cloud.google.com/bigquery/docs/manually-changing-schemas#changing_a_columns_mode" rel="nofollow noreferrer">https://cloud.google.com/bigquery/docs/manually-changing-schemas#changing_a_columns_mode</a>).</p>
  <p>I have 2 questions about that.</p>
  <ol>
  <li><p>What does this last sentence &quot;You can also use the load job to overwrite the existing table&quot; mean? Does this mean I can somehow make this schema change in the existing table and don't actually have to make a new table?</p>
  </li>
  <li><p>I want to avoid creating a new table and just make schema changes to my existing table. <strong>Is there a way to change the mode of a column from NULLABLE to REQUIRED in my existing table?</strong> For other modifications like deleting a column from a table schema or changing a column's data type it is possible to use a query job for that (option 1 in the doc). Is there also a query job I can do to change a column's mode? BigQuery does not seem to support something like &quot;ALTER TABLE [Table] ALTER COLUMN [Column] INTEGER NOT NULL&quot;.</p>
  </li>
  </ol>
  <p>Any help is appreciated!</p>