v_select := ' SELECT MAX (' ||
                determine_column_name(p_tabelnaam,'_date') || ')' ||' FROM ' || p_table_a || ' WHERE ' ||
                here comes the where clause.....
  
    EXECUTE IMMEDIATE v_select
      INTO v_dateA;
  
    IF v_dateA IS NULL
    THEN
    
      v_select := ' SELECT MIN (' ||

here I do the select statement from the other table.
              

    
      EXECUTE IMMEDIATE v_select
        INTO v_dateB;
-- to_char is done because I need this as a string for another dynamic sql function...so the function returns a varchar2.
v_Date := TO_CHAR(v_dateB, 'dd-mm-yyyy HH:MI:SS');
	     RETURN v_date;
      

 END IF;
   END IF;
 
    EXCEPTION
    when NO_DATA_FOUND then
    NULL;
    
  END ;