You work in a company which uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of a SQL Server 2008 instance. There is a database named DB1 in the instance. TheDB1 database includes spatial data types. On DB1 databse, you have to perform a database consistency check to include the spatial indexes. Besides this, you must make sure that you can reduce the effect on the database concurrency to the least. 
So which Transact-SQL statement should you run? （） 

You work in a company which uses SQL Server 2008. You are the administrator of the company database. Now you are in charge of a SQL Server 2008 instance. There is a database named DB1 in the instance. When you are absent, a user will use a login named Mary to log in and maintain the database snapshots. The user has to delete the database snapshots for DB1, so you have to give the appropriate permissions to the user. 
So which database permission should you give the user?（）