SQL²éѯЧÂÊ 100wÊý¾Ý²éѯֻҪ1Ãë

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p4: 2.4
ÄÚ´æ: 1 G
os: windows 2003
Êý¾Ý¿â: ms sql server 2000
Ä¿µÄ: ²éѯÐÔÄܲâÊÔ,±È½ÏÁ½ÖÖ²éѯµÄÐÔÄÜ
SQL²éѯЧÂÊ step by step
-- setp 1.
-- ½¨±í
create table t_userinfo
(
userid int identity(1,1) primary key nonclustered,
nick varchar(50) not null default '',
classid int not null default 0,
writetime datetime not null default getdate()
)
go
-- ½¨Ë÷Òý
create clustered index ix_userinfo_classid on t_userinfo(classid)
go
-- step 2.
declare @i int
declare @k int
declare @nick varchar(10)
set @i = 1
while @i<1000000
begin
set @k = @i % 10
set @nick = convert(varchar,@i)
insert into t_userinfo(nick,classid,writetime) values(@nick,@k,getdate())
set @i = @i + 1
end
-- ºÄʱ 08:27 £¬ÐèÒªÄÍÐĵȴý
-- step 3.
select top 20 userid,nick,classid,writetime from t_userinfo
where userid not in
(
select top 900000 userid from t_userinfo order by userid asc
)
-- ºÄʱ 8 Ãë ,¹»³¤µÄ
-- step 4.
select a.userid,b.nick,b.classid,b.writetime from
(
select top 20 a.userid from
(
select top 900020 userid from t_userinfo order by userid asc
) a order by a.userid desc
) a inner join t_userinfo b on a.userid = b.userid
order by a.userid asc
-- ºÄʱ 1 Ã룬̫¿ìÁË°É£¬²»¿ÉÒÔ˼Òé
-- step 5 where ²éѯ
select top 20 userid,nick,classid,writetime from t_userinfo
where classid = 1 and userid not in
(
select top 90000 userid from t_userinfo
where classid = 1
order by userid asc
)
-- ºÄʱ 2 Ãë
-- step 6 where ²éѯ
select a.userid,b.nick,b.classid,b.writetime from
(
select top 20 a.userid from
(
select top 90000 userid from t_userinfo
where classid = 1
order by userid asc
) a order by a.userid desc
) a inner join t_userinfo b on a.userid = b.userid
order by a.userid asc
-- ²éѯ·ÖÎöÆ÷ÏÔʾ²»µ½ 1 Ãë.
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