Dynamic Table Selection

REPORT zdany_dynamic_select.

* We use some parameters to dynamically control the select, this is not very
* clever but this is just a test program !!
PARAMETER : p_tabnam TYPE tabname DEFAULT 'SFLIGHT',
            p_selfl1 TYPE edpline DEFAULT 'CARRID',
            p_selfl2 TYPE edpline DEFAULT 'CONNID',
            p_selfl3 TYPE edpline DEFAULT 'FLDATE',
            p_selfl4 TYPE edpline DEFAULT 'PRICE',
            p_selfl5 TYPE edpline DEFAULT 'CURRENCY',
            p_where1 TYPE edpline DEFAULT 'PRICE > 300',
            p_where2 TYPE edpline DEFAULT 'AND CURRENCY = ''EUR'''.

FIELD-SYMBOLS :  TYPE ANY TABLE,
                 TYPE ANY,
                 TYPE ANY.

DATA: lt_where    TYPE TABLE OF edpline,
      lt_sel_list TYPE TABLE OF edpline,
      lt_group    TYPE TABLE OF edpline,
      l_having    TYPE string,
      l_wa_name   TYPE string,
      l_sel_list  TYPE edpline,
      dref        TYPE REF TO data,
      itab_type   TYPE REF TO cl_abap_tabledescr,
      struct_type TYPE REF TO cl_abap_structdescr,
      elem_type   TYPE REF TO cl_abap_elemdescr,
      comp_tab    TYPE cl_abap_structdescr=>component_table,
      comp_fld    TYPE cl_abap_structdescr=>component.

TYPES: f_count TYPE i.

* Creation of the output table including a non standard field, f_count
* see ABAP FAQ #14 for more information on this topic
struct_type ?= cl_abap_typedescr=>describe_by_name( p_tabnam ).
elem_type   ?= cl_abap_elemdescr=>describe_by_name( 'F_COUNT' ).
comp_tab = struct_type->get_components( ).



* We remove the unnecessary fields
LOOP AT comp_tab INTO comp_fld.
   IF comp_fld-name <> p_selfl1 AND
      comp_fld-name <> p_selfl2 AND
      comp_fld-name <> p_selfl3 AND
      comp_fld-name <> p_selfl4 AND
      comp_fld-name <> p_selfl5.
         DELETE TABLE comp_tab WITH TABLE KEY name = comp_fld-name.
   ENDIF.
ENDLOOP.

comp_fld-name = 'F_COUNT'.
comp_fld-type = elem_type.
APPEND comp_fld TO comp_tab.

struct_type = cl_abap_structdescr=>create( comp_tab ).
itab_type   = cl_abap_tabledescr=>create( struct_type ).

l_wa_name = 'l_WA'.
CREATE DATA dref TYPE HANDLE itab_type.
ASSIGN dref->* TO .
CREATE DATA dref TYPE HANDLE struct_type.
ASSIGN dref->* TO .

* Creation of the selection fields and the "group by" clause
APPEND p_selfl1 TO lt_sel_list.
APPEND p_selfl1 TO lt_group.
APPEND p_selfl2 TO lt_sel_list.
APPEND p_selfl2 TO lt_group.
APPEND p_selfl3 TO lt_sel_list.
APPEND p_selfl3 TO lt_group.
APPEND p_selfl4 TO lt_sel_list.
APPEND p_selfl4 TO lt_group.
APPEND p_selfl5 TO lt_sel_list.
APPEND p_selfl5 TO lt_group.
APPEND 'COUNT(*) AS F_COUNT' TO lt_sel_list.

* creation of the "where" clause
APPEND p_where1 TO lt_where.
APPEND p_where2 TO lt_where.

* Creation of the "having" clause
l_having = 'count(*) >= 1'.

* THE dynamic select
SELECT          (lt_sel_list)
       FROM     (p_tabnam)
       INTO CORRESPONDING FIELDS OF TABLE
       WHERE    (lt_where)
       GROUP BY (lt_group)
       HAVING   (l_having)
       ORDER BY (lt_group).

* display of the results
LOOP AT  ASSIGNING .
   LOOP AT comp_tab INTO comp_fld.
      ASSIGN COMPONENT comp_fld-name OF STRUCTURE  TO .
      WRITE: .
   ENDLOOP.
   SKIP.
ENDLOOP.