Detach database that deleted in SqlExpress

[sajjadlove]

Hi
I attached a database to SqlExpress.then moved the project to another place and deleted the last project(with it's mdf file).now, i can't attach database in new address to SqlExpress.
when i use from following connection:

Data Source=.\\SQLEXPRESS; AttachDBFileName=|datadirectory|dbName.mdf; Initial Catalog=dbName; Integrated Security=True;User Instance=true

it thrown an exception: 'Database already exsist'
and when i change to following Connection

Source=.\\SQLEXPRESS; Initial Catalog=dbName; Integrated Security=True;User Instance=true

it thrown an exception too:'Can not open database that requested to login'

I'm very confused...
How can i detach last database from SqlExpress?

[sajjadlove]

I found a solution for this problem.i created a folder like last project folder and copied the database in it.it worked and data displayed, but i can't detach it...

when i use from below query:

EXEC sp_detach_db 'D:\last folder\dbName.mdf','true'

give me an error that this database doesn't exists, whereas when i used from following ConnectionStrin g, data displayed:

Data Source=.\\SQLEXPRESS; Initial Catalog=dbName; Integrated Security=True;User Instance=true

would you please help me about this problem???!