Database access in a web service

I'm currently working on a web service implementation to a combined web/desktop application (ie. access from different sources).

Now there are two questions I can't really find an answer to:

1. How would I access the database in the right way (static class? singleton? DI?)? I didn't find any information on using a Web Service in a DI container to help with the database access.

2. What about writing access? Is this the right way to offer a posibility of writing to the database? Of course, the requests would be protected with a userID and a key.

Note: this is NOT wcf, but the normal web servi开发者_如何学Goce (ie. asmx file extension).

There are many "right" ways of accessing a database from a web service. Personally, I often use ADO.NET inside a static class (or, more accurately, a class with a bunch of static methods) that generally returns a DataTable (wrapped in a DataSet, which can be serialized and thus easily returned from a web service). You could also use an ORM (like NHibernate), although these invariably have a larger overhead than ADO.NET and thus are a potential source of load problems on your server.

There's no particular reason not to allow write access to your database from your web service. If your application design requires that the database be written to (obviously a pretty common requirement) then it's perfectly fine to do so from the web service.