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What database should I use for small dotnet Application?

I am developing a small application with ASP and C# in .NET and I want to have a small local database next to it where I can save and retrieve records by either SQL queries or Linq queries. I don't need anything powerful, just something to use instead of keeping records in .txt files.
So what's your suggestion?

Use SQLite
It does not have to be installed and is just a DB File and there are connectors to .Net available.
And you can use LINQ

I would go with either SQLLite or with XML since you are saying very small database.
And with xml you can use Linq to xml

You can use SQL CE or SQLite.

Best to use SQL Express edition since it comes for free. Try using .NET entity framework code first for rapid application development.
In any case application is very small consider using SQL express since you can write neat and clean stored procedures and can play with other database objects.
Please refer http://www.microsoft.com/sqlserver/en/us/editions/express.aspx for more details.

I'll consider SQLite for this purposes.
If you are more comfortable with MS tools, or for some reason (i.e. your company already has a well formed mdb database file) you can use MS Access too, for local and small applications.

I recommend you to use SQL Server Express, becuase
It is free to use and easy to install
You can easily use either Entity Framework or LINQ TO SQL to manipulate your data
It can easily communicate with your company's DB ( if it is also SQL Server), for example, one day in the future, you may need to test the replication.

No one's mentioned it yet so here it is. mySQL and the .Net mySQL client.

In your case I would consider the following:
XML if you don't with more than a couple hundred records in all tables. And #Ali mentioned already LINQ to XML what will be handy.
VistaDB, because it's 100% managed code and require deployment of just one small assembly for both 32- and 64-bit.
SQL CE, just because it's the most popular one. Of course, it supports LINQ and concurrency.
SQLite as an alternative for SQL CE :)
Don't go with SQL Express unless it's been already provided by your hoster. It increases complexity of distributing/installing of your solution.

Which .NET ORM has best support for PostgreSQL database

I'm interested to find out which ORM has best support for Postgres SQL database? Does any mapper have, both, LINQ support and ability to generate model from database?

I haven't compared it against DbLinq but LlbgenPro supports Postgres and is very strong. It supports both Linq and generating the model from the database. In it's just released v3.0 it can generate projects not just for the LlblGen runtime but also for NHibernate, Entity Framework and LinqToSql.
It should be in your list to evaluate.

I would say NHibernate is your friend here.

Quite an old question, but for anyone happening upon this now (like me), please do check out the Marten document & event store for PostgreSQL/.net

DbLinq

You can use NEntityDb. With NEntityDb for PostgreSQL you can query and save data to the database with .NET LINQ Expressions and Fluent API.

Nhibernate HQL SQL Server 2005 / 2008 CONTAINSTABLE

do you know anyway how I to use CONTAINSTABLEvia HQL? I need to use CONTAINSTABLE, not just CONTAINS. Currently I am using a SQL-query, but I need to use the multi-query feature which is not avaiable for SQL right now.
If there is no such thing, would I be able to extend the MSSQL dialect? Or would that require to modify the core of NH?
Thanks in advance!

I have posted a NHibernate patch that will add support for custom SQL queries in a MultiQuery (see NH-2495 on http://jira.nhforge.org).

What's a good "mobile" .NET database that supports LINQ?

I'm in the process of refactoring an application and I've decided to use a mobile/embedded database.
I've been reading about SQL Server Compact Edition, but I was wondering if any of you knew of any other databases that could be used and don't have huge download sizes, as my current application is about ~2MB (installer). SQLite would be nice, but AFAIK the GSoC implementation of LINQ-to-SQLite is rather buggy at the moment.
Thanks!

I have tried out db40 once (not the compact edition) - it is an object database. However, depending on your needs it may be a rather comfortable thing to use. They note that they support linq even for the compact edition:
http://www.db4o.com/s/compactframeworkdb.aspx

VistaDB and (as you mentioned) Sql Server Compact Edition are two small options for an embedded database. Sql Server Compact Edition can be used with Linq to SQL or Entity Framework. I believe VistaDB can be used with the Entity Framework.
Also, if you do not require a relational database, you may want to consider db4o. Rob Conery writes about this here.
Hope this helps!

I haven't used it myself, but you might want to look at BlackFish. I'm not sure about its Linq support though, but Delphi supports Linq so it may. Another may be Embedded Firebird - again, not sure about the Linq side of things.

Can you use LINQ tools such as SQLMetal with an access database?

I'm creating a small database application to teach myself the following concepts
C# programming
.Net 3.5 framework
WPF
LINQ ORM
I want to use Microsoft Access as the database but I can't seem to find any mention of whether its possible to use SQLMetal to generate the ORM code from a Microsoft Access database.
Does anyone know if this is possible?
If not, are there any small database or embedded databases I could use? I think SQL express would be overkill for me at this point.

For an embedded database, you can use SQL Server Compact Edition. Unlike SQL Server Express, it is not compatible with the LINQ to SQL designer, but it is fully compatible with the command-line SQLMetal. It has a few advantages over SQL Express, like to ability to use embedded or run from a file. Microsoft has a very handy chart outlining the differences between Express and Compact.

I don't think SQL Express would be overkill if you want to learn real-world skills - quite the opposite in fact! That'd be my choice, and whatever I chose, I'd stay clear of Access.
Good luck

AFAIK, Linq to SQL is MSSQL server provider specific. To be honest, SQL Express is pretty lightweight on todays machines.
BTW don't confuse LINQ with Linq to SQL. Linq is the underlying technology to provide "query" like support to .NET (amongst other things), where as L2S is effectively a Data Access technology built on top of Linq. Vanilla Linq will work with any ADO.NET provider, which of course Access is one.
Entity Framework will work with any compatible provider also but if SQLExpress is too heavy for you then I wouldn't recommend going down this path...

Thanks for all the responses. I never expected to get an answer this quick. For my test application I think SQL Server Compact Edition would be the way to go. I'm basically creating a money managment app similar to Microsoft Money and although it is an exercise to learn skills, I would eventually want to use it to manage my finances (provided its not too crap!)
This why I thought a fully blown database would be overkill.