I start to learn about database. I have a doubt about the data hierarchy that "file" in the data hierarchy show as below. Does it also include file extension .dat .mp3 or other(binary file). And if it include, What's field and record of it.
bit --> byte --> field --> record --> file --> database
One of the first things you should learn is what a Data Model means and what Physical Data Independence means.
A database is a logical concept: "an organised collection of data". It is arbitrary and meaningless to talk of a database consisting of "files" or "records" unless you are describing an actual DBMS product or have some particular idea about how the database is being implementated in hardware.
So your hierarchy is entirely misleading as a general concept (although it may make sense in certain examples of database systems).