Q:

Store json object in database using php

Quick question, I have a JSON data object for example { "name":"John", "age":30, "car":null } , is it possible to store this just as it is in a mysql field?,  and in turn read it? 

A:

You can store basically whatever you want in a MySQL field, the only constraints are the datatype and maximum size of the field.  Whether that makes sense is another matter, and depends on the your use case.  Two cases that make sense are as follows:
If you simply need a place to store a serialized array/object somewhere, and you don't need to query the fields in the serialized data, you can store it into e.g. a varchar or a text field like any other string, and simply json_encode on the way in and json_decode when reading it.   
On the other hand, e.g. for a use case where you have variable data structures associated with your main table entries, which you need to query, you can use the JSON datatype (available since MySQL 5.7.8).  The JSON datatype only accepts valid JSON strings for input, and there are several useful functions for querying the contents.  
Whatever you do, don't store JSON (or other serialized data) into a regular text field, and then try to query it with LIKE '%"field":"value"%' style hacks.  They yield misery and eventually fail.