On Feb 11, 2007, at 12:54 PM, Robert Garcia wrote:
The transaction works, if you use a lock (read/write exclusive) and
use the select max method, but that is not a good idea on a heavily
trafficed app.
yes, locked. and it hasn't failed in 4 years and there are periods of
high traffic and near simultaneous transactions (knocking on
wood).... using mysql here.
If you are using mssql, you don't need to use a transaction, let me
find the name of that method...
I don't remember the syntax of getting the value, I wouild have to
look up my code, but what you are looking for is @@scopeidentity,
not @@identity. Then a transaction is not needed.
@@scopeidentity gets the last identity inserted, for the current
session/connection.
--
On Feb 11, 2007, at 12:36 PM, Roland Dumas wrote:
what about creating a transaction, inserting the order, and in the
transaction, asking for ... select <@literal @@identity> .. to get
the order's record number? You're not going to get the same
unique ID for two orders coming in at the same time.
On Feb 11, 2007, at 12:26 PM, Robert Garcia wrote:
Do not make the mistake of doing an insert, and asking for the
last ID doing something like select max(rowid) from table. This
works, but it is NOT full proof. If there are 2 orders happening
at the same time, you can get the wrong value, and have 2
sessions pointing to the same order. So, create a GUID
(guaranteed unique identifier) and either use that as the order
key, or use it to retrieve the order id if you want to use the
nice integer id.
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