比较2行+分组Mysql答案

【问题标题】：comparing 2 rows + grouping Mysql比较2行+分组Mysql
【发布时间】：2016-03-30 18:58:53
【问题描述】：

我该怎么做？我搞不清楚了。

╔════════╦══════════╦══════════╗
║ ITEM   ║ PRICE    ║ DATE     ║
╠════════╬══════════╬══════════╣
║ Dollar ║       60 ║ 1.3.2016 ║
║ Dollar ║       50 ║ 2.3.2016 ║
║ Bound  ║      100 ║ 1.3.2016 ║
║ Bound  ║      110 ║ 2.3.2016 ║
║ Euro   ║      600 ║ 1.3.2016 ║
║ Euro   ║      580 ║ 3.3.2016 ║
╚════════╩══════════╩══════════╝

输出应显示每种类型的一个项目，最后价格和与前一行的价格差异

╔════════╦══════════╦════════════════════════╗
║ ITEM   ║ PRICE    ║ DATE     ║ Differnece  ║
╠════════╬══════════╬════════════════════════╣
║ Dollar ║       50 ║ 2.3.2016 ║   -10       ║
║ Bound  ║      110 ║ 2.3.2016 ║    10       ║
║ Euro   ║      580 ║ 3.3.2016 ║   -20       ║
╚════════╩══════════╩════════════════════════╝

【问题讨论】：

真正的问题是什么？
对不起，你现在可以看到了
到目前为止您尝试过什么？如果答案只是想“我迷路了”，那么您需要聘请一名程序员为您做这件事。

标签： mysql sql

【解决方案1】：

select name as 'Item',
       price as 'Price',
       (select max(date) from table where name like '%dollar%') as 'Date',
       (select top 1 price from table where name like '%dollar%') - (select top 1 price from table where id< (select max(id) from table where name like '%dollar%')and name like '%dollar%' order by id desc) as 'difference'
       from table where name like '%dollar%'
union all --now just repeat the code above and switch the like as you want
select name as 'Item',
       price as 'Price',
       (select max(date) from table where name like '%bound%') as 'Date',
       (select top 1 price from table where name like '%bound%') - (select top 1 price from table where id< (select max(id) from table where name like '%bound%')and name like '%bound%' order by id desc) as 'difference'
       from table where name like '%bound%'

【讨论】：

这将是一个缓慢的查询 xD，如果你想快速聘请程序员