mysql查询周流失

Question

前边提问说查周流失率，就是上周登录的人在本周没登录这样的一个人数。
select count(1) from (select distinct playerId from log_login l1 where week(now())-1=week(loginTime) and not exists(select distinct playerId from log_login l2 where l1.playerId = l2.playerId and week(NOW()) =week(loginTime)))t;

现在又让我查各级别的周流失用户数
比如说等级为2-10级这样一个等级段的人上周登录了在本周没登陆的人数。
有好几个阶段 1，2-10，11-20，21-40，41-60，61-80，81-100.
我加上leve>=x and level<=x。这几个查出来的数量比上周登录的总用户还要多！！
不知道是我的sql语句错了，还是数据库的数据有问题。
下面是我的sql语句：
select count(distinct playerId) from log_login l1 where week(now())-1=week(loginTime) and level=1 and not exists(select distinct playerId from log_login l2 where l1.playerId = l2.playerId and week(NOW()) =week(loginTime) and level=1);

Answer 1

select count(distinct playerId) from log_login l1 where week(now())=week(loginTime) and level=1 and not exists(select distinct playerId from log_login l2 where l1.playerId = l2.playerId and week(NOW()) -1=week(loginTime));

去掉 and level=1 否则查询时会造成 很多not exists