1.关于 SQL 查询效率,100w 数据,查询只要 1 秒,与您分享:
机器情况
p4: 2.4
内存: 1 G
os: windows 2003
数据库: ms sql server 2000
目的: 查询性能测试,比较两种查询的性能
SQL 查询效率 step by step
-- setp 1.
-- 建表
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
-- 建索引
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
-- 耗时 08:27 ,需要耐心等待
-- step 3.
select top 20 userid,nick,classid,writetime from t_userinfo
where userid not in
(