PHP MySQL GROUP_CONCAT Limit

Question

I couldn't find wether this was possible so, is there any option to limit a GROUP_CONCAT in MySQL-function?

E.g.:

GROUP_CONCAT(ColName ORDER BY ColName DESC LIMIT 5)

I don't want to use a subquery since this will seriously slow down the performance. I can slice the array later in PHP, but I was wondering or MySQL had an option to achieve this in MySQL already.

Answer 1

No, but you can do this:

SUBSTRING_INDEX(GROUP_CONCAT(ColName ORDER BY ColName DESC), ',', 5)

You may want to pay attention to the group concat maximum length (see group_concat_max_len), if the intermediate string might be larger than 1024 characters. You can change the default.