tell me which database is best while working with asp.net i have many options like sql server msacess oracle
It depends on your needs. But at least don't go for MS Access unless your application is a single user application.
SQL Server Express (2005 or 2008) is a great choice and typically free on most hosts. You can create a database up to 4GB in size and it allows stored procedures and uses the same file format as SQL Server. All in all an excellent choice for a .NET based site.
MS SQL cause its from Microsoft. So, there will less synching problems between SQL and ASP.NET and there is tons of trouble shooting material available. Believe me, we are using ASP.NET with Oracle for some reasons and its certainly not a good ride.
Yes, PHP-MYSQL and .NET-MSSQL are good combinations. However, MySQL has provided the managed component (mysql.data.dll) to deal with MYSQL server on .NET very efficiently.
well it depends you can use ms access if only one users need to connect to teh database. if you want multiple users to connect to the database sql server. however if you don't want to spend money on sql server you can use mysql. i've made 2 years ago in .net an application which is conecting to mysql and worked fine.