What Does The Use Command Do When You Are Working Against A User Instance/attachdb

I have a script from ASP.NET application services. It can be crated using the aspnet_regsql.exe utility in the 2.0 framework. The beginning of the script contains the following:





Code Snippet SQL


DECLARE @dbname nvarchar(128)
DECLARE @dboptions nvarchar(1024)

SET @dboptions = N'/**/'
SET @dbname = N'databasename'

IF (NOT EXISTS (SELECT name
FROM master.dbo.sysdatabases
WHERE name = @dbname))
BEGIN
PRINT 'Creating the ' + @dbname + ' database...'
DECLARE @cmd nvarchar(500)
SET @cmd = 'CREATE DATABASE [' + @dbname + '] ' + @dboptions
EXEC(@cmd)
END
GO

USE [databasename]
GO
I have a database in the App_Data folder in an ASP.NET website project. It shows up in the Server Explorer. But when I run this script on that database, the output seems fine (No rows affected. (0 row(s) returned) etc) but no tables are actually created in the database I ran it on. The database connection string in the Server Explorer has AttachDbFilename and User Instance=True.

So what exactly happens when SQL Server Express executes the CREATE DATABASE and USE [databasename] in this context? Is it ignored, is there now a new database somewhere on my machine, because the script seems to run fine on SOME database, just not the one expected.

Thanks!