Select statement (new to ABAP)

Question

Hi, I just get to know ABAP and have been studying about it. I'm practising an exercise in which i use select statement to retrieve data from many tables with the same field. The tables i use are COSS, AFVC, PRPS and IMZO with the same field OBJNR. The data i need to retrieve is POSNR from table IMZO. This is the code that i've just written. Howvever, when i execute it, it said 'Unable to interpret t_imobj-posnr'. I think the code is not right somehow. Very appreciate any guides.
REPORT  Z_IMPOS_TEST.
TABLES: coss,       "CO Object: Cost Totals for Internal Postings
        afvc,       "Operation within an order
        prps,       "WBS (Work Breakdown Structure) Element Master Data
        imzo.       "Table: CO Object - Capital Investment Prog.Pos.
TYPES: BEGIN OF st_impos,
  objnr       TYPE coss-objnr,
  gjahr       TYPE coss-gjahr,
  pspnr       TYPE prps-pspnr,
  posnr       TYPE imzo-posnr,
END OF st_impos.
DATA : st_imobj    TYPE st_impos,
       t_imobj     TYPE STANDARD TABLE OF st_impos.
*PARAMETERS: p_year TYPE coss-gjahr OBLIGATORY.
SELECT objnr gjahr
      INTO CORRESPONDING FIELDS OF st_imobj
      FROM  coss
      WHERE objnr = st_imobj-objnr
      AND  gjahr = '2007'.
   SELECT objnr
      INTO st_imobj-objnr
      FROM afvc
      WHERE projn = st_imobj-pspnr.
         SELECT objnr
         INTO st_imobj-objnr
         FROM imzo
         WHERE posnr = st_imobj-posnr.
         st_imobj-posnr = st_imobj-posnr.
         st_imobj-gjahr = '2007'.
         APPEND st_imobj TO t_imobj.
         ENDSELECT.
    ENDSELECT.
  ENDSELECT.
  WRITE: 'InvProgPosition is : '  t_imobj-posnr.

Answer 1

thank you everyone. I fixed most of the lines in the code. The syntac is correct now, but since i used nested select statements, it takes like FOREVER to give the output when i execute it!. Are there any other ways to make the code more effecient?
REPORT  z_impos_test.
TABLES: coss,       "CO Object: Cost Totals for Internal Postings
        afvc,       "Operation within an order
        prps,       "WBS (Work Breakdown Structure) Element Master Data
        imzo.       "Table: CO Object - Capital Investment Prog.Pos.
TYPES: BEGIN OF st_impos,
  objnr       TYPE coss-objnr,
  gjahr       TYPE coss-gjahr,
  kstar       type coss-kstar,
  projn       type afvc-projn,
  pspnr       type prps-pspnr,
  posnr       type imzo-posnr,
END OF st_impos.
data: year TYPE coss-gjahr value '2007'.
DATA: t_output  TYPE STANDARD TABLE OF st_impos WITH HEADER LINE,
      st_output TYPE st_impos,
      t_output2 TYPE STANDARD TABLE OF st_impos WITH HEADER LINE,
      st_output2 TYPE st_impos.
SELECT objnr gjahr kstar FROM coss
INTO CORRESPONDING FIELDS OF st_output
WHERE ( objnr LIKE 'NV%' OR
      objnr LIKE 'PR%' ) AND
       gjahr = year.
   SELECT SINGLE projn from afvc into CORRESPONDING FIELDS OF st_output
       WHERE objnr = st_output-objnr.
APPEND st_output to t_output.
ENDSELECT.
SORT t_output BY objnr.
DELETE ADJACENT DUPLICATES FROM t_output.
LOOP AT t_output into st_output.
SELECT objnr pspnr
       INTO CORRESPONDING FIELDS OF st_output2
       FROM prps
       WHERE objnr = st_output-objnr
       AND   pspnr = st_output-pspnr.
  SELECT SINGLE posnr from imzo into CORRESPONDING FIELDS OF st_output2
       WHERE objnr = st_output2-objnr.
APPEND st_output2 to t_output2.
ENDSELECT.
ENDLOOP.
LOOP AT t_output2 to st_output2.
WRITE:   st_output2-posnr.
ENDLOOP.