What is the difference between users and logins in sql server

This means that there is no password associated with a database user. You can check out this at the Login Properties window by right-clicking the newly-created login and select Properties. But when I try to expand the database test , I got the following error message due to lack of database permissions. In order to get access to a specific database, we need to create a new database user and map it to the login jack.

Next, expand the database you want to create a new user on. Expand 'Security' and right click on 'Users' and click on 'New User Leave SQL user with login as the User type.

Specify a new User name. Afterward, click on the browse icon next to the Login name text field. Back at the User window, click on 'Default Schema'.

The Select Schema window will appear. Click on Browse to select a schema for the user. Each of the above objects can have permissions granted to it at its own level. See the following articles for an explanation of each. One reason to have both is so that authentication can be done by the database server, but authorization can be scoped to the database. That way, if you move your database to another server, you can always remap the user-login relationship on the database server, but your database doesn't have to change.

The first important thing that needs to be understood about SQL Server security is that there are two security realms involved - the server and the database. The server realm encompasses multiple database realms. All work is done in the context of some database, but to get to do the work, one needs to first have access to the server and then to have access to the database. Access to the server is granted via logins. There are two main categories of logins: SQL Server authenticated logins and Windows authenticated logins.

I will usually refer to these using the shorter names of SQL logins and Windows logins. Windows authenticated logins can either be logins mapped to Windows users or logins mapped to Windows groups. So, to be able to connect to the server, one must have access via one of these types or logins - logins provide access to the server realm.

But logins are not enough, because work is usually done in a database and databases are separate realms. Access to databases is granted via users. Users are mapped to logins and the mapping is expressed by the SID property of logins and users.

A login maps to a user in a database if their SID values are identical. Depending on the type of login, we can therefore have a categorization of users that mimics the above categorization for logins; so, we have SQL users and Windows users and the latter category consists of users mapped to Windows user logins and of users mapped to Windows group logins.

Let's take a step back for a quick overview: a login provides access to the server and to further get access to a database, a user mapped to the login must exist in the database. I think this is a very useful question with good answer. A login is a security principal, or an entity that can be authenticated by a secure system. Users need a login to connect to SQL Server. You can create a login based on a Windows principal such as a domain user or a Windows domain group or you can create a login that is not based on a Windows principal such as an SQL Server login.

For more information, see Choose an Authentication Mode. As a security principal, permissions can be granted to logins. A login that does not have an associated user account is mapped to the guest user. Conversely, if a database user exists but there is no login associated, the user is not able to log into SQL Server server.

When a database is restored to a different server it contains a set of users and permissions but there may not be any corresponding logins or the logins may not be associated with the same users.

This condition is known as having "orphaned users. When you restore a database backup to another server, you may experience a problem with orphaned users.