Biswa Biswa - 1 month ago 12
MySQL Question

How to use GROUP_CONCAT in a CONCAT in mysql

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


how do I get it into the following format?

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


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

Answer
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;

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

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)

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

You can see it implemented here : SQL Fiddle Demo

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