ok, I manage to solve the problem. Though I do not know why.
What I did is to shift these codes 
===
my $q = new CGI;
my $user = $q->param('user');
my $passwd = $q->param('passwd');
my $action = $q->param('action');
my $s_off_no = $q->param('s_off_no');
==

[download]
and any other validation codes into the subroutine instead of leaving it in the "main". the 'caching' goes away, but I do not know why.

thanks

In reply to Re: Re: CGI or DBI 'cache' problem by slok
in thread CGI or DBI 'cache' problem by slok

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