取决于sql_mode

1. 如果sql_mode含ONLY_FULL_GROUP_BY,则会报错, 如下sql均会报错:
   (group by必须包含所有未聚合字段)

select id,name from db1.t1 group by id;
select id,id1,count(name) from db1.t1 group by id;

2. 若sql_mode不含ONLY_FULL_GROUP_BY, 则上述SQL不报错