JSON Data In Database Work

Can anyone please guide me out how to work on JSON data insert,update & delete work. I have not that much of idea how to work on .

I have done only insert data when i am getting data from server,but how to update data by checking database & server,if data is present or not. Along with how to delete that particular data if the data is not in server.

for (int i = 0; i < jArray.length(); i++) {
                        JSONObject c = jArray.getJSONObject(i);
                        // Saajan databse

                        $id = c.getString("$id");
                        ID = c.getString("ID");
                        Name = c.getString("ContactUserName");
                        Service = c.getString("Service");
                        CreatedOn = c.getString("CreatedOn");

                        SimpleDateFormat inputFormat = new SimpleDateFormat(
                                "yyyy-MM-dd'T'HH:mm:ss");
                        SimpleDateFormat outputFormat = new SimpleDateFormat(
                                "dd MMM yyyy hh:mm a");
                        String sourceDateStr = outputFormat
                                .format(inputFormat.parse(CreatedOn));

                        Date sourceDate = outputFormat.parse(sourceDateStr);

                        Country = c.getString("Country");
                        CompanyName = c.getString("CompanyName");
                        AssignedTo = c.getString("AssignedTo");
                        ProfilePicUrl = c.getString("ProfilePicUrl");

                        sfadb.insertList($id, ID, Service, Name, CreatedOn,
                                CompanyName, Country, AssignedTo,
                                ProfilePicUrl);

                        timeSegments = CreatedOn.split("T");

                        String[] s1 = timeZoneOffset.split(":");

                        sourceTimeZoneOffset = "GMT" + s1[0] + s1[1];
                        TimeZone destTimeZone = cc.getTimeZone();