我有一张table:CREATETABLE`p`(`id`bigint(20)unsignedNOTNULL,`rtime`datetimeNOTNULL,`d`int(10)NOTNULL,`n`int(10)NOTNULL,PRIMARYKEY(`rtime`,`id`,`d`)USINGBTREE)ENGINE=MyISAMDEFAULTCHARSET=latin1;我有一个问题:selectid,d,sum(n)frompwherertimebetween'2012-08-25'anddate(now())groupbyid,d;我正在一个小表(2条记录)上对此查询运行解释,它