Security access to a table
In SQL Server 2008 you can control user access to a table and fields also.All tables and fields are available in the security system, and access can be set up individually for each user group working within a company or domain without affecting other user groups. Table and field access is configured when you set security keys (Administration > Setup > Security > User group permissions on the Permissions tab).
For more information visit following link in Microsoft site:
http://technet.microsoft.com/en-us/library/aa834466(v=ax.50).aspx