如何在MySQL的CONCAT中使用GROUP_CONCAT [英] How to use GROUP_CONCAT in a CONCAT in MySQL

问题描述

如果我在MySQL中有一个包含以下数据的表:

If I have a table with the following data in MySQL:

id       Name       Value
1          A          4
1          A          5
1          B          8
2          C          9

如何将其转换为以下格式?

how do I get it into the following format?

id         Column
1          A:4,5,B:8
2          C:9

我想我必须使用GROUP_CONCAT.但是我不确定它是如何工作的.

I think I have to use GROUP_CONCAT. But I'm not sure how it works.

推荐答案

select id, group_concat(`Name` separator ',') as `ColumnName`
from
(
  select id, concat(`Name`, ':',
  group_concat(`Value` separator ',')) as `Name`
  from mytbl
  group by id, `Name`
) tbl
group by id;

您可以在此处看到它的实现: Sql Fiddle演示 .正是您所需要的.

You can see it implemented here : Sql Fiddle Demo. Exactly what you need.

更新 分两步进行.首先，我们得到一个表，该表具有针对唯一[Name，id]的所有值(用逗号分隔).然后从获得的表中，将所有名称和值作为针对每个唯一ID的单个值 参见 SQL Fiddle演示 (在此向下滚动)有两个结果集)

Update Splitting in two steps. First we get a table having all values(comma separated) against a unique[Name,id]. Then from obtained table we get all names and values as a single value against each unique id See this explained here SQL Fiddle Demo (scroll down as it has two result sets)

编辑:阅读问题时出现错误，我仅按ID分组.但是，如果需要两个group_contacts(值将按名称和ID分组，然后按ID整体分组). 上一个答案是

Edit There was a mistake in reading question, I had grouped only by id. But two group_contacts are needed if (Values are to be concatenated grouped by Name and id and then over all by id). Previous answer was

select 
id,group_concat(concat(`name`,':',`value`) separator ',')
as Result from mytbl group by id

您可以在此处看到它的实现: SQL小提琴演示

You can see it implemented here : SQL Fiddle Demo

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