 | | From: | Will | | Subject: | rowset | | Date: | Mon, 17 Jan 2005 15:15:02 -0600 |
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 | I need to calculate a field and write the field directly to the rowset. How
can this be coded? This is the code I have so far:
form.orderno1.rowset.last()
y = form.orderno1.rowset.fields["orders"].value
form.orderno1.rowset.beginappend()
x = y +1 // incrementing field for order no
form.orderno1.rowset.fields["orders"].value = x (is this correct code for
sending this value to the rowset)
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| | From: | Rick Gearardo | | Subject: | Re: rowset | | Date: | Mon, 17 Jan 2005 16:18:15 -0500 |
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| Yes, it will work (assuming natural order or order number order) if you are
not in a multiuser environment. If this is networked with multiple users you
will be duplicating order numbers because of caching and timing. Multiple
people will see the last order number before a new one is saved().
Rick
"Will" wrote in message
news:bi$1bnN$EHA.1456@news-server...
> I need to calculate a field and write the field directly to the rowset.
How
> can this be coded? This is the code I have so far:
>
> form.orderno1.rowset.last()
> y = form.orderno1.rowset.fields["orders"].value
> form.orderno1.rowset.beginappend()
> x = y +1 // incrementing field for order no
> form.orderno1.rowset.fields["orders"].value = x (is this correct code for
> sending this value to the rowset)
>
>
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| | From: | Will | | Subject: | Re: rowset | | Date: | Mon, 17 Jan 2005 15:27:44 -0600 |
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| this program will be used in a multiuser environment. How can I prevent the
order numbers from being duplicated
"Rick Gearardo" wrote in message
news:cCyQKrN$EHA.876@news-server...
> Yes, it will work (assuming natural order or order number order) if you
> are
> not in a multiuser environment. If this is networked with multiple users
> you
> will be duplicating order numbers because of caching and timing. Multiple
> people will see the last order number before a new one is saved().
>
> Rick
>
> "Will" wrote in message
> news:bi$1bnN$EHA.1456@news-server...
>> I need to calculate a field and write the field directly to the rowset.
> How
>> can this be coded? This is the code I have so far:
>>
>> form.orderno1.rowset.last()
>> y = form.orderno1.rowset.fields["orders"].value
>> form.orderno1.rowset.beginappend()
>> x = y +1 // incrementing field for order no
>> form.orderno1.rowset.fields["orders"].value = x (is this correct code for
>> sending this value to the rowset)
>>
>>
>
>
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| | From: | Marilyn Price | | Subject: | Re: rowset | | Date: | Tue, 18 Jan 2005 07:54:33 -0500 |
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| In article <96RyiuN$EHA.1456@news-server>, toquerrio@hotmail.com says...
> this program will be used in a multiuser environment. How can I prevent the
> order numbers from being duplicated
>
I see Roland has given you one possibility. Another is to have a tiny
table that just holds the most recently assigned number. When you need
a new one, you explicitly lock the rowset with this number in it,
increment the number, save it, then unlock it. Each user gets a unique
number and, if two people attempt to get a value at the same time, the
lock prevents this. Note that the lock is only in place for fractions
of a second, so the delay is minimal.
Something like this:
q = new query()
q.sql := 'select * from "locks.dbf"'
q.active := true
// wait for a rowset lock
do while not q.rowset.lockrow()
enddo
mnext = q.rowset.fields["lastvalue"].value + 1
q.rowset.fields["lastvalue"].value := mnext
q.rowset.save()
q.rowset.unlock()
q.active := false
form.orderno1.rowset.beginappend()
form.orderno1.rowset.fields["orders"].value := mnext
Note: this is untested, but should give you some ideas....
--
Marilyn Price
M. P. Data
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| | From: | Rick Gearardo | | Subject: | Re: rowset | | Date: | Tue, 18 Jan 2005 08:39:33 -0500 |
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| That still doesn't work in the Window's world. You need to put in a delay to
overcome caching and it varies with the amount of users you are going to
have.
I generate various numbers: service call, invoice, po, index keys, etc. I
keep them in a seperate file , along with the delay setting, and increment
them in a loop:
if r.lock()
r.fields["num"].value++
r.save()
for i = 1 to r.fields["myDelay"].value
r.flush()
r.save()
endif
endif
The loop is actually a little more complex but this gives you the idea.
I've had to change the delay a few times as we've added users. It is
currently at 18 which doesn't slow you down but I've eliminated duplicates.
If you are using Windows clients and a Windows server you will probably need
a longer delay because you're overcoming two caching situations.
For index keys I now use a combination of the user's login name and a
generated number. Everyone has a unique login so I don't need a delay.
Rick
> I see Roland has given you one possibility. Another is to have a tiny
> table that just holds the most recently assigned number. When you need
> a new one, you explicitly lock the rowset with this number in it,
> increment the number, save it, then unlock it. Each user gets a unique
> number and, if two people attempt to get a value at the same time, the
> lock prevents this. Note that the lock is only in place for fractions
> of a second, so the delay is minimal.
>
> Something like this:
>
> q = new query()
> q.sql := 'select * from "locks.dbf"'
> q.active := true
>
> // wait for a rowset lock
> do while not q.rowset.lockrow()
> enddo
> mnext = q.rowset.fields["lastvalue"].value + 1
> q.rowset.fields["lastvalue"].value := mnext
> q.rowset.save()
> q.rowset.unlock()
> q.active := false
>
> form.orderno1.rowset.beginappend()
> form.orderno1.rowset.fields["orders"].value := mnext
>
> Note: this is untested, but should give you some ideas....
>
> --
> Marilyn Price
> M. P. Data
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| | From: | Roland Wingerter | | Subject: | Re: rowset | | Date: | Tue, 18 Jan 2005 08:14:04 +0100 |
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| Will wrote:
> this program will be used in a multiuser environment. How can I
> prevent the order numbers from being duplicated
-----
Use dBASE level 7 tables autoinc fields.
Roland
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