How to set field from mail merge to upper case ?

edit

When creating documents on Writer, with the mail merge functionality, I would like to force some fields inserted from the database to be uppercase. Note that, the same field appears on several places, and I would like to conserve the original casing for some of them.

I tried by selecting the field on the template document, then right clicking and selecting the option dedicated to uppercasing, but this is not working: in the generated document, the introduced field from the database keeps it original casing.

So, is it possible to do it?

Thanks :-)

Version: 4.2.8.2; Language: Spanish; Windows 10.