Linq 的速度

[hetengfei_]

//不知下面的语句如何，会不会全表扫描?

var select =( from ps in user.TUsers
// where (ps.UserName.StartsWith("t"))
 orderby ps.id descending
 select new { id = ps.id.ToString(), name = ps.UserName, pass = ps.Password }).Skip(2).Take(5);

相比如下的sql语句 ？

select *from
(
   select  TUsers.id,TUsers.UserName,TUsers.Password,Row_Number()over(order by id desc) as rn, from TUsers  
)as ps
where(ps.rn>=@Index and ps.rn<@Index+@Count)

哪个要快点？ 因为这个 用户表的数据量很大，优化很重要 。

[tptptp00]

Sql Server Profiler

[zh6335901]

你这语句不会全表扫描

[种草德鲁伊]

其实这个都被吐糟过无数次了，linq跟数据库没直接关系

[nfclass]

记录下前后时间 对比下嘛

[挨踢直男]

linq不是转换成sql的吗?

那当然是直接用sql来的快

[tptptp00]

select a.ID,a.Name from TUsers  a 
 inner join  ( 
	select rownum,ID,Name,TypeID,BrandID  from (select ROW_NUMBER() over(order by id) rownum,ID,Name,TypeID,BrandID
	 from TUsers  ) t where  rownum between 0 and 10) as b
	  on a.ID=b.ID order by b.rownum

[tptptp00]

linq比lz的sql快

[骑猪看海]

调试时看下生成的SQL语句

[hetengfei_]

//下面这个就是那个linq 转换成的sql 语句。
大家看看，对比下，那个要好点。//我已把它小写化了，小写好看点

select [t2].[value] as [id2], [t2].[username] as [name], [t2].[password] as [pass]
from (
    select row_number() over (order by [t1].[id] desc) as [row_number], [t1].[value], [t1].[username], [t1].[password]
    from (
        select convert(nvarchar(max),[t0].[id]) as [value], [t0].[username], [t0].[password], [t0].[id]
        from [t_users] as [t0]
        ) as [t1]
    ) as [t2]
where [t2].[row_number] between @p0 + 1 and @p0 + @p1
order by [t2].[row_number]

[Im_Sorry]

那是相当的快！