Load Numerical Column with Variable Comma
Here you go:

SQL&gt; desc loadertst;
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 COL1                                               NUMBER

SQL&gt; !cat loadertst.ctl
load data
infile *
into table loadertst
fields terminated by ',' enclosed by '"'
(
col1 "to_number(replace(:col1,',',''))"
)
begindata
"123456"
"1,2,3,4,5,6"

SQL&gt; !sqlldr phil/phil control=loadertst.ctl

SQL*Loader: Release 11.2.0.2.0 - Production on Thu Nov 29 23:33:17 2012

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Commit point reached - logical record count 2

SQL&gt; select count(*) from loadertst;

  COUNT(*)
----------
         2

SQL&gt;


Obviously you may need to fiddle with the fields terminated by ',' enclosed by '"' part to suit your data.