获取Max（值）而不在SQL Server

Question

我有这个我不需要的分组问题。

这是我创建和播种表的SQL代码：

create table player 
(
    playerid int identity(1,1) primary key,
    Name varchar(255)
)

create table gameplay
(
    gameplayid int identity(1,1) primary key,
    Name varchar(255),
    playerid int references player(playerid)
)

Create table room
(
    Roomid int identity(1,1) primary key,
    number int
)

Create table PC
(
    PCid int identity(1,1) primary key,
    Name varchar(255)
)

Create table playperiod
(
    PKid int identity(1,1) primary key,
    StartDate Datetime null,
    EndDate Datetime null,
    Roomid int references room(roomid),
    PCID int references PC(PCid),
    gameplayid int references gameplay(gameplayid)
)

Insert into player (name) values ('Kris')
Insert into player (name) values ('Bart')
Insert into player (name) values ('Bob')
Insert into player (name) values ('John')
Insert into player (name) values ('Iris')

insert into room (number) values (1000)
insert into room (number) values (1001)
insert into room (number) values (1002)
insert into room (number) values (1003)
insert into room (number) values (1004)
insert into room (number) values (1005)
insert into room (number) values (1006)
insert into room (number) values (1007)
insert into room (number) values (1008)
insert into room (number) values (1009)
insert into room (number) values (1010)

insert into gameplay (name, playerid) values ('WOW', 1)
insert into gameplay (name, playerid) values ('LOL', 2)
insert into gameplay (name, playerid) values ('DIablo', 3)
insert into gameplay (name, playerid) values ('Starcraft', 4)
insert into gameplay (name, playerid) values ('Borderlands', 5)

insert into PC (name) values ('Dell (1)')
insert into PC (name) values ('HP (1)')
insert into PC (name) values ('Dell (2)')
insert into PC (name) values ('HP (2)')
insert into PC (name) values ('Dell (3)')
insert into PC (name) values ('HP (3)')
insert into PC (name) values ('Dell (4)')
insert into PC (name) values ('HP (4)')
insert into PC (name) values ('Dell (5)')
insert into PC (name) values ('HP (5)')
insert into PC (name) values ('Dell (6)')
insert into PC (name) values ('HP (6)')
insert into PC (name) values ('Dell (7)')
insert into PC (name) values ('HP (7)')
insert into PC (name) values ('Dell (8)')
insert into PC (name) values ('HP (8)')
insert into PC (name) values ('Dell (9)')
insert into PC (name) values ('HP (9)')
insert into PC (name) values ('Dell (10)')
insert into PC (name) values ('HP (10)')

truncate table playperiod

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 10:02:00.000', '2015-01-22 11:30:00.000', 1, 1, 1)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid)   
values ('2015-01-22 10:02:00.000', '2015-01-22 16:02:00.000', 1, 2, 2)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 10:04:00.000', '2015-01-28 10:02:00.000', 2, 3, 3)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-20 10:02:00.000', '2015-01-22 10:02:00.000', 2, 4, 4)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 22:40:00.000', '2015-01-22 22:50:00.000', 3, 5, 1)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 22:55:00.000', '2015-01-22 23:50:00.000', 3, 6, 1)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 11:30:00.000', '2015-01-22 13:30:00.000', 1, 1, 1)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 14:30:00.000', '2015-01-22 16:30:00.000', 1, 1, 1)

insert into playperiod (StartDate, EndDate, Roomid, PCID, gameplayid) 
values ('2015-01-22 19:30:00.000', '2015-01-22 22:30:00.000', 1, 1, 1)

知道这些是我的疑问：

步骤1）获取所有内容1天（到目前为止没问题）

Select startdate, number, pc.name, gp.Name,p.Name  
from playperiod PD
left join room R on R.Roomid = PD.Roomid
left join pc on pc.PCid = PD.PCID
left join gameplay gp on GP.gameplayid = PD.gameplayid
left join player P on P.playerid = GP.playerid 
where 
DATEDIFF(day, pd.startdate, '2015-01-22') >= 0 and DATEDIFF(day, pd.startdate, '2015-01-22') <= 0

步骤2）从开始日期获取最大日期值（问题构成）

Select max(startdate) as startdate, number, pc.name, gp.Name,p.Name  
from playperiod PD
left join room R on R.Roomid = PD.Roomid
left join pc on pc.PCid = PD.PCID
left join gameplay gp on GP.gameplayid = PD.gameplayid
left join player P on P.playerid = GP.playerid 
where 
DATEDIFF(day, pd.startdate, '2015-01-22') >= 0 and DATEDIFF(day, pd.startdate, '2015-01-22') <= 0
group by number, pc.name, gp.Name,p.Name

最后我做了分组，所以行为是正确的。但在这里用户＆＃39; Kris＆＃39;那天在2个房间里玩3个人。

但我想有这种情况：

• 只有最大开始时间与该房间号/个人电脑/游戏/名称（该行）
• 我只需要最新的情况。 （即使他改变了电脑或房间）

以下是我需要的结果：

任何人都可以帮助我吗？