求下面代码的详细注释，每个方法实现的功能！

Declare @DatabaseName        sysName
Declare @PrimaryName        sysName
Declare @LogName        sysName
Declare @Path            sysName
Declare @PrimaryFileName    sysName
Declare @LogFileName        sysName
Declare @BackUpFileName        nvarchar(4000)

Select     @DatabaseName         = '%Database%' ,
        @PrimaryName        = @DatabaseName + '_Data' ,
        @LogName            = @DatabaseName + '_Log'  ,
        @Path                 = '%DatabasePath%'              ,
        @PrimaryFileName    = @Path + @PrimaryName + '.mdf' ,
        @LogFileName        = @Path + @LogName + '.ldf' ,
        @BackUpFileName        = '%BackUpPath%'



Use %Database%

Declare @OldPrimaryFile        nvarchar(1000)
Declare @OldLogFile        nvarchar(1000)

Select @OldPrimaryFile = Name
    From sysFiles
    Where FileId = 1

Select @OldLogFile = Name
    From sysFiles
    Where FileId = 2

Use Master

Declare @Id        Int
Declare @cmd    Varchar(1000)

Declare c Cursor For
    Select spid
        From master..sysprocesses
        Where hostname  <> ''

Open c


Fetch Next From c Into @Id

While(@@FETCH_STATUS<>-1)
Begin
    If(@Id <> @@SPID)
    Begin
        Select @cmd = 'Kill ' + Cast(@Id as Varchar)
        Execute(@cmd)
    End
    Fetch Next From c Into @Id
End

Close c
Deallocate c

Declare @RestoreCommand nVarchar(4000)

Select @RestoreCommand ='
RESTORE FILELISTONLY
   FROM DISK = ''' + @BackUpFileName + ''''


Execute(@RestoreCommand)