有条件的左联接中的查询问题

Question

I have this query which helps me to get the points for a current user, now, i have a problem on setting a condition...

$query4 =  'SELECT u.*, SUM(c.ts) AS total_sum1, SUM(r.bv) AS total_sum 
FROM users u 
LEFT JOIN 
 (SELECT user_id ,SUM(points) AS ts FROM coupon GROUP BY user_id) c 
 ON u.user_id=c.user_id AND u.user_id="'.$_SESSION['user_name'].'"
LEFT JOIN 
 (SELECT user_id ,SUM(basket_value) AS bv FROM retailer GROUP BY user_id) r 
ON u.user_id=r.user_id 
GROUP BY u.user_id';

My problem is the AND u.user_id="'.$_SESSION['user_name'].'"

I need to find the points for this specific user.. Am i doing something wrong with it? I mean, i know i am, but what? Thanks

Answer 1

write your query like this

$query4 =  'SELECT u.*, SUM(c.ts) AS total_sum1, SUM(r.bv) AS total_sum 
FROM users u 
LEFT JOIN 
 (SELECT user_id ,SUM(points) AS ts FROM coupon GROUP BY user_id) c 
 ON u.user_id=c.user_id 
LEFT JOIN 
 (SELECT user_id ,SUM(basket_value) AS bv FROM retailer GROUP BY user_id) r 
ON u.user_id=r.user_id 
where u.user_id="'.$_SESSION['user_name'].'"
GROUP BY u.user_id';