mysql-版本的行列转换
2022/8/6 2:25:32
本文主要是介绍mysql-版本的行列转换,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
mysql版本的行列转换
先看一个题目
方法:
行转列
--我们可以使用union all函数 将其凭借起来 select ( case id when 1 then 'first' when 2 then 'second' when 5 then 'fifth' end)grade ,sum( case subject when 'chinese' then score else 0 end) chinese ,sum( case subject when 'math' then score else 0 end) math ,sum( case subject when 'politics' then score else 0 end) politics from test group by id;
行转列
select * from ( select (case grade when 'first' then 1 when 'second' then 2 when 'fifth' then 5 end) id, 'chinese' subject, chinese as score from test2 union all select (case grade when 'first' then 1 when 'second' then 2 when 'fifth' then 5 end) id, 'math' subject, math as score from test2 union all select (case grade when 'first' then 1 when 'second' then 2 when 'fifth' then 5 end) id, 'politics' subject, politics as score from test2 order by id) a where a.score<>0;
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