Hi,
You can use the ABAP command "Export to Data Buffer" and "Import from Data Buffer" to convert your internal table to xstring or other way.
Data: lt_export type table of BUT000,
lt_import type table of BUT000,
lv_db type xstring.
Export LV_DATA = LT_EPORT to data buffer lv_db.
Import LV_DATA = LT_IMPORT from data buffer lv_db.
Thanks
Deepak