MYSQL Group Concat Select Some Selected Rows Only

Its so simple. Just need to do below thins:

SELECT SUBSTRING_INDEX(GROUP_CONCAT(x.id ORDER BY x.nx DESC), ',', 2) as row_name from some_table GROUP BY some_field

It will select First two values only.

It total value of GROUP_CONCAT is "1,2,3,4,5" Then Using SUBSTRING_INDEX would be like "1,2"

You can use DISTINCT in GROUP_CONCAT function like SUBSTRING_INDEX(DISTINCT(GROUP_CONCAT(x.id ORDER BY x.nx DESC)), ',', 2)