Calc.View: How to check if a field contains character?

Hi Experts!

I have to check if a field is numeric, i.e., if there is only numbers with no character.

The output field is called CFOP, using SAP HANA Calculation View type SQL Script, the WHERE condition below DOES not work:

WHERE "CFOP" not like '%[a-z]%'.

I either do not know how to achieve this using Graphical Calculation View.

Does anyone have an idea how to check if a field contains a character?

Thanks in advance!

Leandro