Creation of Table type with out using structure

Hi experts,

I want to create a table type with single field and without referring to the structure at DB level.

Can I refer to any data element, If this is possible how to use this Table type.

I have created a table type by referring to Data element but not able to use it.

For example..

ztt_mattnr is a table type which is referring to matnr.

When I am trying to use it for For all entries it is throwing me an error.

     data it_mara type ztt_mattnr.

     SELECT * FROM maraINTO TABLE lt_mara

              FOR ALL ENTRIES IN it_mara

              WHERE matnr= it_mara-matnr.

How to overcome this ?

BR,

Eshwar