是不是改了变量以后需要重新连接一下才会生效？
和你下面类似的sql，我执行后报错。
1055 - Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'battleLog.battlelog.datetime' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by