2021-12-01 SQL学习7

课程资料网盘链接：https://pan.baidu.com/s/1-jOwaXWArtv8h21B0-uWGg 提取码：wsra
SQL零基础入门笔记：https://www.mubucm.com/doc/4VC7JuHlj6H
云端数据库安装文档：https://share.mubu.com/doc/rBUGcUie8H
Python安装文档：https://www.mubucm.com/doc/4DJ8YNSNz4F

https://sqlzoo.net/wiki/window_LAG

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select
recovered 累计治愈人数
,case when recovered = 1 then 'one' when recovered >1 then 'more' else '0'
end
from covid
where recovered > 0

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