As of now there is no proper way to quit from an ongoing restore....if anyway you interrupt the restore process, the state of the database will be set to 1 and the database property 'IsShutDown' for the database is set to null....and there is no way of updating the system tables with adhoc queries......so its upto the MS SQL Server Development team to provide the feature of restore rollback in the next version......
Chandrachurh Ghosh
DBA – MS SQL Server
Ericsson India Global Services Limited
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