[ic] How to disable update database twice when browser's reload action

[murahashi]

Hi,all

How can I disable database update in Interchange page when browser's reload
button?

(Page-A)
---Form input several variables.
[set UPDATE]
mv_todo=return
[/set]
<input type="submit" NAME=mv_click value="UPDATE">

(Page-B)
---update database based on variables.
---send emails to users

In my case, when user clicks reload button at Page-B, update database and
send emails again.
To control this, I tried to add some tags like below.

(Page-A)
 From input several variables.
[set UPDATE]
mv_todo=return
db_update=yes
[/set]
<input type="submit" NAME=mv_click value="UPDATE">

(Page-B)
[if value db_update eq yes][value name=db_update set=no][/if]
[if value db_update eq no][bounce href="[area index]"][/if]
---update database based on variables.
---email send to users

But that does not work. After reload button pushed, Variable db_update is
still yes.

This is what I want to do. Please help me or any suggestion.
Thanks.
Murahashi