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RE: ADO.NET - A Data Access Layer

Igor Makedon — Wed, 03 Aug 2005 07:06:00 GMT

Does DAL refuse Data-Binding approach? In other words can it be used when one wants a GUI control (as opposed to developer's SQL code) to take care about SELECT / UPDATE / INSERT / DELETE?

I am having problems with an old application relying heavily on data binding. It needs to migrate to .NET. The database gradually became pretty ugly during its many-years lifetime.

I'd love to create / use a DAL approach which seems to be the only way to maintain the application's being up and running while "remodeling" is being in progress. But...

What about the first question in this post please?

RE: ADO.NET - A Data Access Layer

Renato Buda-153382 — Wed, 04 Aug 2004 22:11:00 GMT

I agree with all Patryks reasons for using a data access layer.I also re-iterate rugha's comment - see the microsoft SqlHelper class which they publish separately as a freely downloadable Data Access Application Block.This allows the coder to use static methods to perform most data access tasks which makes things much easier. You can of course build on this to do logging etc...http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/daab-rm.asp

RE: ADO.NET - A Data Access Layer

Zvonko M. — Tue, 03 Aug 2004 08:00:00 GMT

Hi all,

My DAL starts with Stored Procedures and prepared commands and we use .NET framework components with corresponding typed datasets. Then you can drop your DAL Component and needed datasets to Win/WebForm and call its methods. It is good idea to create typed dataset properties in your component so it will allow you to select dataset instance using IDE property editor - cheers!

Common DAL "framework" should be comprised of component base classes. That's how I see this problem. Btw, when you use SqlCommand object's parameters collection, "sql injection" is not a problem any more.

Have a nice day

RE: ADO.NET - A Data Access Layer

Tatsu — Tue, 03 Aug 2004 07:58:00 GMT

The Data Access Application Block is really quite excellent. This is also another opportunity to plug Code Generation. I know, I know, I promised to write an article on the topic and I started one but it sucked I'll get back to work on it soon.

My point is, you should not have to write 80% of the stored procedures or any of the data access layer. Let a code generator do the generic stuff for you. Check out CodeSmith at http://www.ericjsmith.net/codesmith/ or the Code Generation Network at http://www.codegeneration.net/.

RE: ADO.NET - A Data Access Layer

rugha — Tue, 03 Aug 2004 07:25:00 GMT

havent read the whole article, just wanted to let you know about the "Data Access Application Block" published by microsoft for that exact purpose, it is quite easy to use, details and downloads can be found here :

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/daab-rm.asp

cheers

rugha

RE: ADO.NET - A Data Access Layer

Greg Walker — Tue, 03 Aug 2004 07:04:00 GMT

A few issues I see with this approach. I'm curious as to your opinion on them:

1) It does nothing to prevent SQL injection attacks. I can pass in something like "select * from table ; delete * from table", which would qualify as a select statement, but would execute both the select and the delete statement. Very dangerous and hard to catch.

2) Aren't you losing all the benefits of running stored procs by using sp_executesql? None of the queries are running against pre-compiled sprocs that way, and some queries can be very long and complex (much more than 1000 characters).

Again, I really like the idea of a data access layer (it's been on our development list for a while now). I'm just not sure what the best approach is for it. I prefer to require the client to access all data through stored procedures (we develop a web based app), which makes it hard to develop a generic interface.

Just my $0.02. I'm curious to hear what other people think.

Greg WalkerDBAExpenseWatch.com

RE: ADO.NET - A Data Access Layer

Tony Hinkley — Tue, 03 Aug 2004 05:38:00 GMT

Razvan raises a good point, and one that reinforces the suggestion that a data layer is a good idea. It's much easier to prevent SQL Injection and the like in a dedicated data layer, than on every individual SQL call.

Tony

RE: ADO.NET - A Data Access Layer

Razvan Socol — Tue, 03 Aug 2004 04:04:00 GMT

Patrick,

You wrote "we have to ensure that the SQL command passed to the procedure is actually a SELECT statement". I hope that you realize that the statement could be something like this:

SELECT 1 DELETE _t_spsys_select_log WHERE log_id=(SELECT MAX(log_id) FROM _t_spsys_select_log)

This means that we must trust the developer of the client application to give us a correct SELECT statement. This means that we trust that he only uses hard-coded strings or if he uses anything entered by the user, he validates them very well. If anyone wants to read further on this topic, see:

http://www.nextgenss.com/papers/advanced_sql_injection.pdf

Razvan

ADO.NET - A Data Access Layer

Patryk Nowakowski — Fri, 16 Jul 2004 11:31:00 GMT

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