What is the usage of for all entries ?

Question

What is the Usage of read table  after using for all entries ?
In the following example what exactly it is doing ?
  Usage of 'for all entries' in Select Statement
FORM data_retrieval.
  DATA: ld_color(1) TYPE c.
  DATA: BEGIN OF T_VBAP OCCURS 0,
        VBELN  LIKE VBAP-VBELN,
        MATNR  LIKE VBAP-MATNR,
        POSNR  LIKE VBAP-POSNR,
        END OF T_VBAP.
  DATA: BEGIN OF T_VBFA OCCURS 0,
        VBELV  LIKE VBFA-VBELV,
        VBELN  LIKE VBFA-VBELN,
        VBTYP_N  LIKE VBFA-VBTYP_N,
        END OF T_VBFA.
  DATA: BEGIN OF T_VBAK OCCURS 0,
        VBELN  LIKE VBAK-VBELN,
        IHREZ  LIKE VBAK-IHREZ,
        END OF T_VBAK.
  DATA: BEGIN OF T_KNA1 OCCURS 0,
        KUNNR  LIKE KNA1-KUNNR,
        NAME1  LIKE KNA1-NAME1,
        END OF T_KNA1.
   DATA: BEGIN OF T_MAKT OCCURS 0,
        MATNR  LIKE MAKT-MATNR,
        MAKTX  LIKE MAKT-MAKTX,
        END OF T_MAKT.
  SELECT likpvbeln likplifex likpbldat likpwadat likpwadat_ist likpkodat likp~lfart
         likpkunnr likpvstel lipsposnv lipslfimg lipsvrkme lipslgmng lips~meins
         lipswerks lipslgort lipscharg lipsvbelv lipsposnr lipsmatnr
         lipsvbeln LIPSVGBEL LIPSVGPOS vbupkosta vbupwbsta vbupposnr vbup~vbeln
          VBAKIHREZ VBAKVBELN VBAP~VBELN
     INTO CORRESPONDING FIELDS OF TABLE  it_itab
    FROM ( likp
           INNER JOIN lips
           ON  lipsvbeln = likpvbeln
           INNER JOIN vbup
           ON  vbupposnr = lipsposnr
           and VBUPVBELN = LIPSVBELN )
          left outer join VBAK
          on  VBAKVBELN = LIPSVGBEL
          inner join VBAP
          on  VBAPVBELN = VBAKVBELN )
         WHERE likp~vbeln IN so_vbeln
           AND likp~lifex IN so_lifex
           AND likp~lfart IN so_lfart
           AND likp~kunnr IN so_kunnr
           AND likp~vstel IN so_vstel
           AND likp~bldat IN so_bldat
           AND likp~wadat_ist IN so_wadat
           AND vbup~kosta IN so_kosta
           AND vbup~wbsta IN so_wbsta
           AND LIPS~LFIMG NE 0.
  SELECT VBELN IHREZ INTO TABLE T_VBAK
  FROM VBAK
  FOR ALL ENTRIES IN  IT_ITAB
  WHERE VBELN = IT_ITAB-VGBEL.
APPEND T_VBAK.
ENDSELECT.
  SELECT VBELN MATNR POSNR INTO TABLE T_VBAP
  FROM VBAP
  FOR ALL ENTRIES IN  IT_ITAB
  WHERE VBELN = IT_ITAB-VGBEL AND
        MATNR = IT_ITAB-MATNR AND
        POSNR = IT_ITAB-VGPOS.
APPEND T_VBAP.
ENDSELECT.
  SELECT VBELV VBELN VBTYP_N INTO TABLE T_VBFA
  FROM VBFA
  FOR ALL ENTRIES IN  IT_ITAB
  WHERE VBELV = IT_ITAB-VBELN AND
        VBTYP_N = 'M' .
  SELECT KUNNR NAME1 INTO TABLE T_KNA1
  FROM KNA1
  FOR ALL ENTRIES IN IT_ITAB
  WHERE KUNNR = IT_ITAB-KUNNR.
APPEND T_KNA1.
ENDSELECT.
  SELECT MATNR MAKTX INTO TABLE T_MAKT
  FROM MAKT
  FOR ALL ENTRIES IN IT_ITAB
  WHERE MATNR = IT_ITAB-MATNR.
APPEND T_MAKT.
ENDSELECT.
*Populate field with color attributes
  LOOP AT it_itab INTO wa_ITAB.
Populate color variable with colour properties
Char 1 = C (This is a color property)
Char 2 = 3 (Color codes: 1 - 7)
Char 3 = Intensified on/off ( 1 or 0 )
Char 4 = Inverse display on/off ( 1 or 0 )
i.e. wa_ekko-line_color = 'C410'
    REFRESH color.
    colourize 'VBELN' 0. " .
    WA_ITAB-farbe = color[].
    ld_color = ld_color + 1.
Only 7 colours so need to reset color value
    IF ld_color = 3. "8
      ld_color = 1.
    ENDIF.
    CONCATENATE 'C' ld_color '10' INTO wa_ITAB-line_color.
    WA_ITAB-NAME1 = ''.
    WA_ITAB-MAKTX = ''.
    WA_ITAB-IHREZ = ''.
    WA_ITAB-VBELV = ''.
    READ TABLE T_KNA1 WITH KEY KUNNR = WA_ITAB-KUNNR.
    IF SY-SUBRC = 0.
       WA_ITAB-NAME1 = T_KNA1-NAME1.
    ENDIF.
    READ TABLE T_MAKT WITH KEY MATNR = WA_ITAB-MATNR.
    IF SY-SUBRC = 0.
    WA_ITAB-MAKTX = T_MAKT-MAKTX.
    ENDIF.
    READ TABLE T_VBAK WITH KEY VBELN = WA_ITAB-VGBEL.
    IF SY-SUBRC = 0.
    WA_ITAB-IHREZ = T_VBAK-IHREZ.
    ENDIF.
    READ TABLE T_VBFA WITH KEY VBELV = WA_ITAB-VBELN.
    IF SY-SUBRC = 0.
    WA_ITAB-VBELVA = T_VBFA-VBELN.
    ENDIF.
   READ TABLE T_VBAP WITH KEY VBELN = WA_ITAB-VGBEL
                              POSNR = WA_ITAB-VGPOS
                              MATNR = WA_ITAB-MATNR.
   IF SY-SUBRC = 0.
   WA_ITAB-IHREZ = T_VBAK-IHREZ.
   ENDIF.
wa_ekko-line_color = 'C410'.
    MODIFY it_itab FROM wa_itab.
  ENDLOOP.
ENDFORM. " data_retrieval

Answer 1

hi Jyotirmoy,
The explanation below can give u an idea of wat is going in ur code..
Use of FOR ALL Entries
Outer join can be created using this addition to the where clause in a select statement. It speeds up the performance tremendously, but the cons of using this variation are listed below
Duplicates are automatically removed from the resulting data set. Hence care should be taken that the unique key of the detail line items should be given in the select statement.
If the table on which the For All Entries IN clause is based is empty, all rows are selected into the destination table. Hence it is advisable to check before-hand that the first table is not empty.
If the table on which the For All Entries IN clause is based is very large, the performance will go down instead of improving. Hence attempt should be made to keep the table size to a moderate level.
Not Recommended
            Loop at int_cntry.
             Select single * from zfligh into int_fligh
             where cntry = int_cntry-cntry.
             Append int_fligh.
            Endloop.
Recommended
            Select * from zfligh appending table int_fligh
            For all entries in int_cntry
            Where cntry = int_cntry-cntry.
Thankyou,
Regards.