There are many ways to do this.. First format the cloumns you want to select to make them as characters. then select all the columns from table and create a spool file. this will solve your purpose.

A sample file is mentioned below.. Try to get help from this..



cat <<EOD > $TmpFileName
spool $SpoolFileName

set heading off
set termout off
set feedback off
set pagesize 0
set linesize 240
set colsep ' '

-- set the column format.

col CUST_ID format a10
col HDR_ID format a10
col ITEM_NO format a10
col SAP_MTL_NBR format a18
col MTL_DSCR format a80
col MTL_GRP format a10
col PLNG_QTY format a30
col UOM format a4
col SLS_ORG format a10
col PLANT format a10
col OMAD_DTE format a10
col CREATE_DTE format a10



--**********************************************************************
-- selects the Heading
--**********************************************************************
SELECT distinct
'CUST_ID' CUST_ID,
'HDR_ID' HDR_ID,
'ITEM_NO' ITEM_NO,
'SAP_MTL_NBR' SAP_MTL_NBR,
'MTL_DSCR' MTL_DSCR,
'MTL_GRP' MTL_GRP,
'PLNG_QTY' PLNG_QTY,
'UOM' UOM,
'SLS_ORG' SLS_ORG,
'PLANT' PLANT,
'OMAD_DTE' OMAD_DTE,
'CREATE_DTE' CREATE_DTE
FROM dual;
--**********************************************************************
-- selects the records
--**********************************************************************
SELECT H.Trade_Cust_ID CUST_ID,
H.Ord_Hdr_ID HDR_ID,
I.Ord_Ln_Item_ID ITEM_NO,
I.SAP_Mtl_nbr SAP_MTL_NBR,
M.Mtl_Dscr MTL_DSCR,
M.Mtl_Grp_ID MTL_GRP ,
TO_CHAR(NVL(I.Ord_Plng_Unt_Qty,0),'099999999999.999') PLNG_QTY,
'PU' UOM,
H.SAP_SLS_ORG_ID SLS_ORG,
I.Plant_ID PLANT,
TO_CHAR(I.Orig_OMAD_Dte,'MM/DD/YYYY') OMAD_DTE,
TO_CHAR(I.Create_Dte,'MM/DD/YYYY') CREATE_DTE
FROM
tab1 H,
Tab2 I,
tab3 M
WHERE
-----;

spool off;
/
quit
EOD

${ORACLE_HOME}/bin/sqlplus user_id password $TmpFileName 1>> \
$LogFileName 2>&1



Hope it will help you to come out of your problem.