You can use SOAP API to update column properties in an existing data extension to change how the data extension handles information. For example, you can change the number of characters allowed in a field.
We recommend that you use REST API operations to update data extensions instead of using SOAP API. See UpdateDataExtension.
Note
Sample SOAP Envelope
To modify a field in a data extension, you must specify the ObjectID for the DataExtensionField object. If you don’t specify an ObjectID, SOAP API adds a new column with the same name as the existing column, which produces an error. Use the Retrieve method on the DataExtensionField object to find the ObjectID.