Modifing user data

Sometimes you can modify the data to make it less harmful.

Example:  You want to
Read an SQL select statement from the user.
Allow reads only, no updates, etc.

   $_=param('sql');

   s/ ^ \s* select \s+ //xg;  # strip the initial 'select'

   $_ = "select $_";          # put it back

   $_ =~ s/ \b into \b /;     # remove the ability to use
                              # 'select ... into'

This can break though.  (All 'into's removed...)