How Can I Order Concatenated Values within SQL's GROUP_CONCAT Function?

GROUP_CONCAT Functions Enhanced with ORDER BY

In SQL, the GROUP_CONCAT function is used to concatenate values from a column for a particular group of rows. However, the order of the concatenated values is usually unpredictable.

The Challenge:

Consider the following table:

client_id	views	percentage
1	6	20
1	4	55
1	9	56
1	2	67
1	7	80
1	5	66
1	3	33
1	8	34
1	1	52

By performing a GROUP_CONCAT operation, the data is consolidated:

SELECT li.client_id, group_concat(li.views) AS views, group_concat(li.percentage) FROM li GROUP BY client_id;

Output:

client_id	views	percentage
6,4,9,2,7,5,3,8,1	20,55,56,67,80,66,33,34,52

However, the order of views is not as required. To organize the concatenated values in ascending order, an ORDER BY clause can be incorporated within the GROUP_CONCAT function:

SELECT li.client_id, group_concat(li.views ORDER BY li.views) AS views, group_concat(li.percentage ORDER BY li.views) FROM li GROUP BY client_id

The modified query returns the following output:

client_id	views	percentage
1	1,2,3,4,5,6,7,8,9	52,67,33,55,66,20,80,34,56

This modification ensures that the views column is arranged in ascending order within each client group.

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