I'm retreiving a JSON string and parsing it with jQuery with $.getJSON.
After I get the data in a variable, can I add or remove rows? An example:
{"one": [{"sid":"1","name":"NAME 1"},{"sid":"2","name":"NAME 2"}],
"two": [{"sid":"3","name":"NAME 3"}]}
Can I delete sid 1 from "one" and place it in "two"? How about sorting by sid? I'm using jQuery.
Sure, just evaluate the JSON document to JavaScript objects, and work on them.
sure, you can do any of that, they are regular objects and arrays. You can sort arrays, remove their members, add members to other arrays, etc. I wouldn't use jquery stuff, just use basic array tools, such as splice and push and pop. splice() can do most anything: http://www.w3schools.com/jsref/jsref_splice.asp
Sorting is easy as well, just use sort() on the arrray.
"After I get the data in a variable" - unless this variable is holding a string, which it probably isn't, it's not really JSON at that point - your question is a bit vague. JSON is an encoded form of data, usually used for sending information over a network or for storage on disk. It's a way to serialize information.
It could be used as the backend storage for a small "database". This kinda depends on your definition of "database" - if you're thinking generic relational database, yes, it can, inefficiently.
Your post however, makes it sound like you got some data and loaded it into a variable, which isn't really "using JSON as a database".