Re: Navigation question

On Feb 14, 2:22 pm, "Carl Federl" <cfed..._at_yahoo.com> wrote:
> <Do large, production-quality, highly usable and useful, data-based,
> read-and-write software applications actually exist where there is no
> code in the software that navigates around the database?
>
> Yes, there are many large, production-quality, highly usable and
> useful that do not have any database navigation performed by the
> application.

The formatting on this one isn't easy for me to read, Carl, but I'll give it a spin. I'm working to figure out precisely what "database navigation" means to others, particularly to those who oppose it. So, from this statement I believe that there are such applications that perform no "navigation" as you understand the term, which might not be how I have previously understood the term.

> Picture a data entry screen with header information about a company
> and a list of orders presented to the user. Are applications written
> where the exclusive approach would be to read all of the data in and
> write the data back using a single view?>
> Typically not using views, although that is possible, but instead
> persistent stored modules (ISO term) are used.
> SQL DBMS vendors have implemented three type of persistent stored
> modules:
> Stored procedures that be invoked from an application
> Triggers that automatically run when a table action occurs (insert,
> update or delete)

Yes, the are pooh-poohed by some theorists, as I understand it.

> User-derfined function that can be referenced in a SQL statement but
> cannot be called by the application.
>
> There are also been a lot of success with using XML both as output and
> input with stored procedures as in this example:
>
> create view CustomerOrderProducts as
> SELECT Customers.CustomerID
> , Customers.CompanyName
> , Orders.OrderDate
> , Orders.ShippedDate
> , OrderProducts.OrderID
> , OrderProducts.ProductId
> , Products.ProductName
> , OrderProducts.UnitPrice
> , OrderProducts.Quantity
> , OrderProducts.DiscountPct
> FROM Customers
> join Orders
> on Orders.CustomerID = Customers.CustomerID
> join OrderProducts
> on OrderProducts.OrderID = Orders.OrderID
> join Products
> on Products.ProductId = OrderProducts.ProductId
> go
> create procedure CustomerOrderProducts_CustomerId ( _at_CustomerId
> nvarchar(4)) as
> select * from CustomerOrderProducts
> where CustomerId = _at_CustomerId
> order by Customers.CustomerID , OrderProducts.OrderID ,
> OrderProducts.ProductId
> as XML AUTO
> go
> create procedure CustomerOrderProducts_OrderId (_at_OrderID integer)
> as
> select * from CustomerOrderProducts
> order by Customers.CustomerID , OrderProducts.OrderID ,
> OrderProducts.ProductId
> as XML AUTO
> go
> The output of the CustomerOrderProducts_OrderId for orderId = 10248
> is:
>
> <Customers CustomerID="VINET" CompanyName="Vins et alcools Chevalier">
> <Orders OrderDate="1996-07-04T00:00:00"
> ShippedDate="1996-07-16T00:00:00">
> <OrderProducts OrderID="10248" ProductId="11" UnitPrice="14.0000"
> Quantity="12">
> <Products ProductName="Queso Cabrales" DiscountPct="0.0000000e+000"/></
> OrderProducts>
> <OrderProducts OrderID="10248" ProductId="42" UnitPrice="9.8000"
> Quantity="10">
> <Products ProductName="Singaporean Hokkien Fried Mee"
> DiscountPct="0.0000000e+000"/></OrderProducts>
> <OrderProducts OrderID="10248" ProductId="72" UnitPrice="34.8000"
> Quantity="5"><Products ProductName="Mozzarella di Giovanni"
> DiscountPct="0.0000000e+000"/></OrderProducts>
> </Orders></Customers>
>
> As you can see, there is no application navigation of the database.

Yes. I haven't seen a statement like this before, so very interesting. Thanks.

> For inputs, an application can accept messages, convert to XML and
> then provide XML to a stored procedure which will:
> Convert the XML into virtual relations
> Perform the appropriate Insert, Updates and Deletes to the underlying
> tables - in this example, Customers, Orders and OrderProducts

OK, thanks. I do understand that if using XML you get some of the features I seek. I have heard the term "navigation" with XML too, as if RM is better than XML because you navigate in the latter but not the former. I am sure I'm understanding the anti-navigation incorrectly, however. Thanks. --dawn Received on Thu Feb 15 2007 - 22:19:31 CET