Granting a Windows User or Group Access to a Database
To obtain access to a Microsoft® SQL Server™ database, a Microsoft Windows NT® 4.0 and Windows® 2000 user or group must have a corresponding user account in each database they need to access. Additionally, permissions must be applied to this user account.
Although possible, it is not necessary to add an individual user account in a database for each Windows NT 4.0 and Windows 2000 user in a Windows NT 4.0 and Windows 2000 group whose members all perform the same activities. Accounts can be added for groups rather than for each individual member. When the group members need to work in a database, they are granted access through their membership in the Windows NT 4.0 and Windows 2000 group; there is not a specific account for individual users within the group. For example, a Windows NT 4.0 and Windows 2000 group London\Managers contains the Windows NT 4.0 and Windows 2000 user London\JoeB. The SQL Server system administrator grants login access only to London\Managers. The owner of database Accounts grants only London\Managers permission to access Accounts. Although London\JoeB does not have explicit permission granted to connect to an instance of SQL Server or to access Accounts, he can connect to the instance of SQL Server and access Accounts due to his membership in London\Managers.
Add individual Windows NT 4.0 and Windows 2000 users to a database only if the user performs activities different from other members of any Windows NT 4.0 or Windows 2000 group (for example, special database administrative duties).
Note Users who are granted access to an instance of SQL Server through their memberships in a Windows NT 4.0 or Windows 2000 group do not have entries for their individual Windows NT 4.0 or Windows 2000 user accounts in the system tables. However, an entry is created for their individual user accounts if they create objects, such as a table or a stored procedure, in a SQL Server database.
To grant a Windows user or group access to a database
Transact-SQL