Editing Column
Option Edit Column allows you to change the column name, data type, add and delete column attributes, make the column nullable, a key column or a distribution key column. The option is available on the Table Details page.
Perform the following steps to edit a column.
On the left sidebar, click TABLES to open the Tables page.
On the Tables page, click the name of the table containing the column to be edited. This will open its Table Details page.
On the Table Details page, under the Columns tab, click the More Options icon related to the column and select Edit Column.
In the Edit Column dialog, change the required parameters and click Save.