1. Hibernate: how to use CONCAT and GROUP_CONCAT

How can I use CONCAT() and GROUP_CONCAT() in HQL queries?

2. How to deal with group_concat in Hibernate / Grails?

I have a table "mydata", containing 1 row per day per group:

id        bigint(20) PK
fromdate  date
mygroup   varchar(255)
myvalue   double
I need to ...