Databases Reference
In-Depth Information
5.
The website has a constraint that an item cannot be shipped more times than
it was ordered. If data is presented to the website that attempts to ship an
order line that has already been shipped, the import process to the website
will fail, requiring manual intervention. For standard merchandise items,
this is unlikely to happen as we can assume that the supplier system has
sufficient control to prevent double-shipping. However, we need to develop
a control for this scenario for two reasons; firstly, because, although the
supplier systems might also not allow double shipping, a file from a supplier
might get presented twice in an error; and secondly, in splitting the order
to our different suppliers, we have sent each supplier a notification of the
delivery SKU. As a result, the delivery SKU will always be presented more
than once on orders that contained items from multiple suppliers.
This is a key consideration for us in this job. To deal with this, we'll do
two things:
° As we process the data, we'll look up the current shipping status
within the website application. Any order items presented from a
supplier that are already shipped in the website database will
be ignored.
° Before we create a new order status update file for the website
based on data from the suppliers, we'll check that the website is
not already processing a previous order status update file. Without
this check, we could find ourselves in a situation where order line
ID, 12345, is waiting to be processed by the website, when the same
data is presented, in error, from a supplier datafile. If we check the
database at this point, the order item will not have been shipped, so
it will be passed through to a new order status update file. However,
simply checking the database does not tell us that the same data is in
a file waiting to be processed. If we wait until the first file has been
processed by the website, we can be sure that the database status is
correct and up-to-date.
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