SQL：返回用户的最新操作列表

I have a table as follows:

我有一张表如下:

CREATE TABLE useractions
(
    id INT PRIMARY KEY NOT NULL AUTO_INCREMENT,
    user_id INT,
    modified BIGINT, //this is the time of the action in milliseconds
    status INT,      // 1 = placed, 2 = processing ,3 = shipping or 4 = completed, 5 = failed
    action_id INT    // 1 = buy, 2 = sell, 3 = exchange, etc
);
CREATE