Why does this mysql query give me garbage results?

Question

Im trying to get the total amount of points a user has, as well as current month's points. When a user gets a point, it gets logged into the points table with a timestamp. Totals ignore the timestamp, while the current month's points looks for the points with the correct timestamp (from the first day of the month).

SELECT user_id, user_name, sum(tpoints.point_points) as total_points, sum(mpoints.point_points) as month_points
FROM users 
LEFT JOIN points tpoints
ON users.user_id = tpoints.point_userid 
LEFT JOIN points mpoints 
ON (users.user_id = mpoints.point_userid AND mpoints.point_date > '$this_month')
WHERE user_id = 1
GROUP BY user_id

points table structure

 CREATE TABLE IF NOT EXISTS `points` (
  `point_userid` int(11) NOT NULL,
  `point_points` int(11) NOT NULL,
  `point_date` int(11) NOT NULL,
  KEY `point_userid` (`point_userid`),
  KEY `point_date` (`point_date`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

This results in a very large number, thats equal to the sum of all points, multiplied by the number of rows that match the query.

I need to achieve this without the use of subqueries or multiple queries.

Answer 1

SELECT user_id, user_name, 
       (
       SELECT  SUM(points.point_points)
       FROM    points
       WHERE   points.point_userid = users.user_id
       ) AS total_points,
       (
       SELECT  SUM(points.point_points)
       FROM    points
       WHERE   points.point_userid = users.user_id
               AND points.point_date > '$this_month'
       ) AS month_points
FROM   users 
WHERE  user_id = 1

Answer 2

try

SELECT user_id, user_name, sum(point_points) as total_points, sum( case when point_date > '$this_month' then point_points else 0 end ) as month_points
FROM users
    LEFT JOIN points
        ON users.user_id = points.point_userid 
WHERE user_id = 1
GROUP BY user_id, user_name