Create column if not exists

I have totranslate this oracle script into hana script

declare

x number;

begin

    select count(*) INTO x from user_tab_cols where table_name = 'EM_WEB_SERVICE_PARAMETRI' and column_name = 'TIPO_FILTRO_DATI';

    if x=0 then

       begin

          execute immediate ('ALTER TABLE EM_WEB_SERVICE_PARAMETRI ADD TIPO_FILTRO_DATI VARCHAR2(30) NULL');

       end;

    end if;

end;

/

i have see  IF EXISTS | SAP HANAbat this SP not give error and not delete table

How can Itranslatethis script?

Can I do a script similar to oracle and I do not a SP?

You can help me?

Another question: how can I getautomaticallythe schema name?

thanks Paola