You should take a look at the examples coming with the library, it is often useful.
You have to use msql.next() to get the next row of information. Usually programs loop on this call to get all the rows, or use a more specific request to get only one.
Also I don't know what you have in your Size variable. It might contain "Size" (a string) or 1 (first column of the request).

I have been using an example. Size is a column in my table, that I wish to take information from. Here's the full code. I'm able to insert a declared variable into my table. I just want to know how to do the opposite.

Read again my answer, please.