Is it necessary to delete a database before restoring the backup in MySQL? As a rule, I always drop the database, and then create a new one and only after that restore a dump file. But I'm wondering, is it necessary to do? 

For example, if I lose some data and begin to restore my database, why I cannot just to restore it, like in MS SQL, without deleting it first?
Read the first few lines of the dump -- Does it say DROP DATABASE or anything like that?

(There are many options on mysqldump that control whether drops, creates, etc, are emitted into the dump, so there is no single answer to this question.)