phpforlife

Okay so i know this is going to sound really stupid i just got out of school and now im in the real world here is the problem I dont know very much about how to work with JSON via PHP all i am trying to do is have the Script read data into an array from some text boxes then from the array into a JSON file the reading and the listing is all fine and dandy but only if i want the entire file how do i read data from a JSON file and only have it display data according to what i want so for example if i wanted to return data that matched an ID like you would do in MySQL like this ("SELECT * FROM catagories WHERE ID = '$id'") so how do i do that without a Database using a JSON File as a source for the data 18121_.php 18122_.php