First Use of DataWrangler

First, we will replace the transformation used to rename the column Id to Id_external with a DataWrangler:

To do this, add a DataWrangler transformation from the "Others" section.

Once added, connect its left input to ClientExternalInfo and its right output to JoinDB. You can now remove the previous column renaming step. Rename this new transformation to "RenameColumn" so that it looks like this:

At this stage, it is normal for the Debug to display errors due to mismatches in field names, transformations, etc. Open the configuration of the new DataWrangler step and select the ID column:

Expanding the right-side action menu will reveal all the transformations available for this column:

We are interested in RenameColumn. Click on it, and a form will appear:

After applying the transformation, you will see the column name change in the data table:

If you make a mistake, you can always delete or edit the transformation from the history menu on the right:

Finally, update the JoinDB transformation to reference the new transformation step:

Once this is done, the Debug should stop displaying errors.