SELECT I.uname,
C.consume,
O.name,O.dis_count,O.memberType,
D.name,D.dis_count,D.up,D.down,
CASE
WHEN D.dis_count IS NULL THEN O.dis_count
ELSE D.dis_count
END AS discount
FROM (
sdb_membermanage_members AS I
LEFT JOIN sdb_membermanage_moneyanddiscount AS C
ON I.member_id = C.member_id
)
LEFT JOIN (
sdb_membermanage_member_lv AS O
LEFT JOIN sdb_membermanage_lv_detail AS D
-- using (member_lv_id)
ON O.member_lv_id = D.member_lv_id
)
ON I.member_lv_id = O.member_lv_id
WHERE O.memberType = ‘1‘
OR (O.memberType = ‘0‘
AND C.consume >= D.down
AND C.consume < D.up
)
解释一下, 目的是 根据会员id 查询出会员的折扣.
涉及到的表: 会员表,会员消费表,会员等级表,会员等级详情表
会员等级表有两种类型的会员，自定义会员和等级会员．会员等级详情
会员等级表里的等级会员是一整套的会员方案 类似于京东的金牌银牌,淘宝的钻石皇冠(即,金牌会员 和银牌会员 的会员等级id相同,具体区别在会员等级详情表里)
会员表里存了 会员消费表表id, 会员等级id
如果是等级会员,则还要继续查询等级会员详情表,
原文：http://www.cnblogs.com/helkbore/p/5135206.html