如何使用java在MySQL中插入JSONObject？

Question

I'm trying to insert a JSONObject that contains a couple of JSONArrays in it inside a MySQL database that I have.

This is what I'm currently trying to do:

JSONObject fiveMin = new JSONObject();
JSONArray data = new JSONArray();
data.add(45);

fiveMin.put("data", data);

String query = "UPDATE frame_data.all_frame_data" 
            + "SET 5_min_data = " + fiveMin
            + " WHERE stock_id = 1";

stmt.executeUpdate(query);

However, it's giving me a null pointer exception.

Anyone know how to fix this? I've been stuck on this for days

Answer 1

your Query is not correct you need a space after frame_data.all_frame_data because this now look like frame_data.all_frame_dataSET 5_min_data , change your Query to be like this :

String query = "UPDATE frame_data.all_frame_data SET 5_min_data = " + fiveMin
            + " WHERE stock_id = 1";

Second i don't think that there are a type JSONObject in MySql so i think you are using a varchar or a text to store your data, so fiveMin should convert to a String and not set like you do for example :

fiveMin.toString();

You query should look like this :

String query = "UPDATE frame_data.all_frame_data SET 5_min_data = '" + fiveMin.toString()
            + "' WHERE stock_id = 1";

I suggest to use PreparedStatement you can learn more here : PreparedStatement

Thank you.