SQL Server, database already exists, backup or restore operation terminateing abnornally

1. Manually create database with existing mdf file gives Cannot create file because it already exists

Hello,

Can someone point me to a FAQ or otherwise help me install this database.  I 
have an MDF file from a VS 2005 Pro Project that I would like to play with. 
I am using SQL 2005 that came with VS 2005.  I am trying to use SQL Server 
Management Studio to create the database but when I do I get an error 1802 
(Cannot create file because it already exists).

How do I create a database with an existing MDF?

Cheers!
Jeff 

2. Re-installed SQL 7 and trying to use already existing db's without doing a restore

3. REcovery model for a backup/restore operation

Hello,

I want to do a backup and restore operations of my base, using SQLCMD.exe.

For that, I use backup database mybase to disk='File'

Then, I try to do a backup of transact log but like this:

backup log mybase to disk='File'

But I have this message : Cannot do a backup log on database which is a 
simple recovery model.

I read the BOL and I saw there are to type of recovery model: Simple and 
full. But I didn't understand  very well explications in BOL.

My questions are:

What are this models???

When are they used ???

Thanks

4. How to check if database already exists - SQL Server

5. Error 15023 : User or role "abc" already exists in current database

I have restored a database which has tables belonging to a 
particular user account created.  However, after 
restoration, I am not able to see the user account in the 
User/Logins item and not able to create a new account with 
the same name and making it the db_owner at the same time.

The system gives me this error.

Using sp_helpusers for this database, I realised that 
there is a user account with the name "abc" but there  is 
no value in the "loginName" & "DefDBName" fields.

Please advise how I can sync this.

Thanks.

6. Error 15023: User already exists in current database - SQL Server

7. User already exists in the database error

I have backed up the SQL database on server X.

I have restored that database to server Y. This server was named the same as 
server X and has the same IP. After restoring the database everything looks 
fine, until I get ready to create users in the "Logins" section of Enterprise 
Manager.

Apparently the imported database already has the same user name associated 
to it that I am trying to create and tells me that the user already exists. I 
am unable to create the "Logins"

Do you think I will get away if I create the "Logins" first and then restore 
the database afterwards?

Thanks

8. Create database when mdf already exists - SQL Server