Assume that two students are trying to register for a course in which there is only one open seat. What component of a database system prevents both students from being given that last seat?

$$ Suppose you want to build a video site similar to YouTube. Consider each of the points listed in Page$12-13$ as disadvantages of keeping data in a file$-$processing system. Discuss the relevance of each of these points to the storage of actual video data, and to metadata about the video, such as title, the user who uploaded it$,$ tags, and which users viewed it$.$