Copy the contents of one field to another in AD

I'm trying to copy the contents of one field to another in AD, I have tried SQL but it did not work, can you suggest how to structure the sentence. I share an example of which I have built:

/* update CN=Users,DC=** set telephoneNumber=ipPhone subtreescope */

Thanks for your help

You can't assign one field to another using sql statement. To assign values to another attribute, please try the following:

1. Click a container or an entry| Right Click Context menu select - Export - Update Statements| Provide the file Name | Click on Browser button adjacent to Returning Attributes and select attribute (for e.g telephoneNumber)| Click Finish
2. Open the exported file using Textpad| Globaly replace the attribute (telephoneNumber) to the new attribute name| Save the file
3. Click Import|SQL from the top tool bar and Click the Start Importing.. Button.
4. Refresh the entry, the new attribute should have the old field value.

Note: Please test with one entry and in a test environment before applying in production.