I have a table ActivityTable and i want to move some records to a Archive table and then delete those moved records from the main table ie the ActivityTable.

I am doing the following

 INSERT INTO ArchiveTable
   ([Id]  ,
   [Name]  ,
   [Key]  ,
   [RegDate]  ,
SELECT top 1000
   [Id]  ,
   [Name]  ,
   [Key]  ,
   [RegDate]  ,       
   FROM ActivityTable
   WHERE registrationDate < cast(cast(dateadd(day, -10, getutcdate()) as Date) as DateTime) 


    DELETE
    FROM ActivityTable
    WHERE registrationDate <  cast(cast(dateadd(day, -90, getutcdate()) as Date) as DateTime)   

How can i be sure that the top 1000 that have been selected will the the exact 1000 that are deleted from the Activity Table ?