create json using concat in mysql stored procedure

Question

I am trying to create a json string in store procedure,

below is my code:

  SELECT 
            CONCAT("[",
              GROUP_CONCAT(
                CONCAT("{roomid:'",roomId,"'"),
                    CONCAT(",participant1:'",participant1),
            CONCAT(",participant2:'",participant2),"'}")
                )
                ,"]") 
            AS json FROM cmChatRooms;

I am following above link , and want out put like this

mysql throws syntax error and I am not able to get the error.

Answer 1

yupi i got that working, silly syntax mistake, corrected & now it worked as i wish

    SELECT 
            CONCAT("[",
              GROUP_CONCAT(
                   CONCAT("{roomid:'",roomId,"'"),
                   CONCAT(",participant1:'",participant1),"'}")
             ,"]") 

AS json FROM cmChatRooms;