Hi Cyril
MySQL GroupConcat function can be an option for this, but I am not sure if the best one. In order to make it work you have to
1) Add the alias to the result e.g. group_concat(...) AS event_data
2) Create a free sotrage (no table selected) field called event_data
3) You have to explode the output in php using explode() function to get an array
What to watch out for
1) Use a good separator in groupconcat function, not just comma, if the concatenate data are strings. the best is to use some asci character
2) The default maximum length of groupconcat function output string is 1024, in case you have larger output, you have to extend it somehow.
Good Luck
Michal