From: Erland Sommarskog on
Rajesh (rajeshhalyal(a)gmail.com) writes:
> is there any way where the database is not even visible to
> administrator.

No.

> or cannot be restored from backup by any other user or
> password.

Transparent Data Encryption, a feature available in SQL 2008 Enterprise
Edition permits you to protect data at rest.

--
Erland Sommarskog, SQL Server MVP, esquel(a)sommarskog.se

Links for SQL Server Books Online:
SQL 2008: http://msdn.microsoft.com/en-us/sqlserver/cc514207.aspx
SQL 2005: http://msdn.microsoft.com/en-us/sqlserver/bb895970.aspx
SQL 2000: http://www.microsoft.com/sql/prodinfo/previousversions/books.mspx