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Posted by Erland Sommarskog on 06/15/07 21:35
Mo (le_mo_mo@yahoo.com) writes:
>
> I have attached to an MDF file through my SQL 2000 enterprise manager.
> I fyou click on Users for this database in the MMC you see the
> following:
>
> Name Login Name DataBase Access
> --------- ------------------
> --------------------------
> Administrator permit
> d_xxxxx permit
> dbo sa permit
>
> When I run my web application through my com+ object I am getting the
> following error
>
> [Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user
> 'd_xxxxx'
>
> The question is why there is no login name for d_xxxxx user? does it
> have a significance? I am new to this and I do not see anywhere in
> the web application where I can set the password.
In SQL Server there are principals (to use the terminology adopted in
SQL 2005) on two levels: server and database. A server principal is
also knowns as a login and a database principal is a user.
A login is what you need to connect to SQL Server. If there is no
login for you, you cannot connect. But just because there is a login
for you, does not mean you can access every database. Your login must
map to a user within the database you want to access.
As long as you work within a single server, this is not very tricky.
You create a login, and then a database user for that login.
But when you move databases between server, things get a bit complicated.
Let's say that on the target server there was a login Sture, and there
was a database where Sture was a user. Now you move that database to a
different server. How would Sture be able to access the database on the
new server? Obviously, he needs a login, so you create one. But he still
cannot access the database. Why? Because the mapping is not simply on
the name. In fact, SQL Server permits Sture to have the username
ErikXIV in a database if the DBA sees fit. Instead the mapping is on
something called SID. And typically SIDs are different from server to
server.
The way to address this situation is to use the stored procedure
sp_change_users_login, read about it in Books Online. But if there is
no login for d_xxxx you need to creat that first.
--
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx
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