Which HTTP headers match certain methods?

I want to make a database where I store data from HAR files. Specifically, I want, by European standards, to store the following headers from HTTP requests and responses.

• content-type
• cache-control
• pragma
• expires
• age
• last-modified
• host

In order to make an efficient MySQL database though, I need to categorise them in a way where I get the least amount of empty columns. Problem is, that I cannot find any information about which types of request/responses get specific headers.

The idea is to make different ISA tables for request and headers where I include the headers that will definitely be included in the corresponding request/response.

I think it might have to do with the method of the request, but I have not found ANY info about that online