mysql中分组函数的写法

字数 1008阅读 1558评论 0赞 3

--max最大值所有行
select it.user_id, 
       it.income,
       case
          when @maxVal is not null then @maxVal := @maxVal
          when @maxVal is null then @maxVal := it.income
       end AS sum_income
from income_tl it, (select @maxVal:=null) r
order by it.income

select it.user_id, 
       it.income,
       @maxVal := IFNULL(@maxVal,it.income)
from income_tl it, (select @maxVal:=null) r
order by it.income

--max最大值，分组行
select it.user_id, 
       it.income,
       case
          when @preVal = it.user_id then @maxVal := @maxVal
          when @preVal := it.user_id then @maxVal := it.income
       end AS sum_income
from income_tl it, (select @preVal:=null, @maxVal:=null) r
order by it.user_id asc, it.income asc;

--按顺序求最大值
select it.id,it. income 
,case
when @maxVal >= it. income  then @maxVal
else @maxVal := it. income 
end AS max_ income 
from  income_tl  it, (select @maxVal := null) r
order by it.id asc, it. income  desc

参考：
https://blog.csdn.net/tangtong1/article/details/50996669/

MySQL

著作权归作者所有

如果觉得我的文章对您有用，请点赞。您的支持将鼓励我继续创作！

添加新评论0 条评论

Ctrl+Enter 发表

匿名评论

mysql中分组函数的写法

添加新评论0 条评论

作者其他文章

相关文章

相关问题

相关资料