what is group_concat in mysql code example

Example 1: group by mysql and concatenate string

mysql> select Id,group_concat(Name SEPARATOR ',') as GroupConcatDemo from GroupConcatenateDemo
   -> group by Id;

Example 2: mysql group concat

/* By deafult separe itens by "," */
group_concat(p.nameItem) as listProdItem
/* Used <br> to list itens one below the other in HTML page */
group_concat(p.nameItem separator '<br>') as listProdItem