asked on
preventing update of customer balance twice
I have a web application using coldfusion and mysql. There is a form where
customer's payment is entered and submitted. Upon submission customer's
balance is updated. Sometimes customer's balance is updated twice.
How do I prevent this from happening?
Example:
Balance: 1000
payment: 100
After update: balance = 800
Thanks.
customer's payment is entered and submitted. Upon submission customer's
balance is updated. Sometimes customer's balance is updated twice.
How do I prevent this from happening?
Example:
Balance: 1000
payment: 100
After update: balance = 800
Thanks.
MySQL Server
Last Comment
SonnyRey
Without seeing your code, it's hard to make specific suggestions. But one solution is to generate a unique identifier, something like a transaction or order id. When the user clicks submit, the application should check if payment has already been made for this id. If so, then it has found a duplicate payment.
ASKER
how do you make a unique id? Cannot make a unique id based on time.
You can just use an integer primary key column + auto_increment
ASKER
This is my code for updating the balance.
<cfquery name="updBal" datasource="#dsn#">
update cust
balance = balance - #form.payment#
</cfquery>
<cfquery name="addToTransact datasource="#dsn#">
insert into transact
(name, payment, pay_date)
values
('#form.name#', '#form.payment#', #Now()#)
</cfquery>
Transact table and cust table have primary id (transactid and custid)
Sometimes this piece of code is executed twice. When that happens transactid
is incremented twice for the two records inserted.
How would a primary key come into play?
Thanks.
<cfquery name="updBal" datasource="#dsn#">
update cust
balance = balance - #form.payment#
</cfquery>
<cfquery name="addToTransact datasource="#dsn#">
insert into transact
(name, payment, pay_date)
values
('#form.name#', '#form.payment#', #Now()#)
</cfquery>
Transact table and cust table have primary id (transactid and custid)
Sometimes this piece of code is executed twice. When that happens transactid
is incremented twice for the two records inserted.
How would a primary key come into play?
Thanks.
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ASKER
That might work. Let me try it.
Thanks.
Thanks.