1，我创建createtime字段时，提示有一个datatime类型，设置这个类型和bigint类型有什么区别吗？
2，我运行insert into 语句时，可以正常给表内对应字段插入值，但是会报这个错，网上找到解决办法是给目录下的my.ini加一些东西，但加完也没用_{这是为啥啊}：

[SQL]INSERT into users(username, `password`,realname) VALUES('lisi','123','李四')

受影响的行: 1
时间: 0.006s

[Err] 1055 - Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'information_schema.PROFILING.SEQ' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by