mybatis 关于 if test 判断字符串的大坑

http://www.javashuo.com/article/p-zzkzqyon-cm.html

还有XML文件 不能用> <来表达大于小于 。。 例如 grade>0 , grade<10

https://blog.csdn.net/zheng0518/article/details/10449549

老周一直遇到的bug

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今天遇到的一个数据查询 的难题

就是统计 评价当前电影 各星星等级 的人数

问题：搜mysql 同一字段 相同的值 的条数

找到解决办法的博客:http://www.javashuo.com/article/p-szyrnqlz-kw.html

我最后写出的语句是这样的：

select m.id,m.name,COALESCE(startb.one,0) as onestar,COALESCE(startb.two,0) as twostar,COALESCE(startb.three,0) as threestar,COALESCE(startb.four,0) as fourstar,COALESCE(startb.five,0) as fivestar from movie m  LEFT JOIN  (SELECT id,star,movie_id,sum(case star when 1 then 1 else 0 end) as one, sum(case star when 2 then 1 else 0 end) as two,sum(case star when 3 then 1 else 0 end) as three ,sum(case star when 4 then 1 else 0 end) as four ,
sum(case star when 5 then 1 else 0 end) as five  from score where movie_id =5) as startb on  startb.movie_id = m.id

springboot 的静态文件 问题