How to Read data base table at runtime

Question

Hi,
  i have an internal table with two fields they are
   tablename and field name.
itab has some entries.
like :
  itab-table name   itab-fieldname
  kna1              kunnr
  mara              matnr
  vbuk              vbeln
  tvak              auart
  i want to read these tables with field names.
like :
loop at itab
   select singe * from <itab-tablename> into <jtab>
      where <itab-fieldname > = <dyanmic value from       prog>.
endloop.
Is it possible to read the db table in the above scenario.
Please try to give me the solution.
Thanks,
srik

Answer 1

Hi, try this example program.
report zrich_0002 .
data: begin of itab occurs 0,
      tabname(20) type c,
      fldname(20) type c,
      end of itab.
data: ref_descr type ref to cl_abap_structdescr.
data: where_clause(100) type c occurs 0 with header line.
data: it_details type abap_compdescr_tab,
      wa_details type abap_compdescr.
data: new_table type ref to data,
      new_line  type ref to data,
      it_fldcat type lvc_t_fcat,
      wa_it_fldcat type lvc_s_fcat.
field-symbols: <dyn_table> type standard table,
               <dyn_wa>,
               <dyn_field>.
start-of-selection.
  itab-tabname = 'T000'.
  itab-fldname = 'MANDT'.
  append itab.
  itab-tabname = 'T001'.
  itab-fldname = 'BUKRS'.
  append itab.
  loop at itab.
* Get the structure of the table.
    refresh it_fldcat.
    refresh where_clause.
    ref_descr ?= cl_abap_typedescr=>describe_by_name( itab-tabname ).
    it_details[] = ref_descr->components[].
    loop at it_details into wa_details.
      clear wa_it_fldcat.
      wa_it_fldcat-fieldname = wa_details-name .
      wa_it_fldcat-datatype = wa_details-type_kind.
      wa_it_fldcat-inttype = wa_details-type_kind.
      wa_it_fldcat-intlen = wa_details-length.
      wa_it_fldcat-decimals = wa_details-decimals.
      append wa_it_fldcat to it_fldcat .
    endloop.
    if <dyn_table> is assigned.
      refresh <dyn_table>.
      unassign <dyn_table>.
    endif.
* Create dynamic internal table and assign to FS
    call method cl_alv_table_create=>create_dynamic_table
                 exporting
                    it_fieldcatalog = it_fldcat
                 importing
                    ep_table        = new_table.
    assign new_table->* to <dyn_table>.
    concatenate itab-fldname '<> ''' '''' into where_clause
                    separated by space.
    append where_clause.
    select * from (itab-tabname) into table <dyn_table>
                  where (where_clause).
  endloop.
Regards,
Rich Heilman