从数据库中选出100个符合要求的行，怎么再从中随机选出10个输出？

[km168]

如题

[saucer]

1. if you are using SQL Server, just do it on the database side, for example

select top 10 * from yourtable .... order by NewID()

2. if you insist to do it in the code, try something like,

DataTable dt; //your data
int nCount = 10;

DataTable dt2;

if (dt.Rows.Count > nCount)
{
int[] indexlist = new int[dt.Rows.Count];
for (int i=0; i < indexlist.Length; i++)
indexlist[i] = i;

Random r = new Random();
int nlast = indexlist.Length - 1;
for (int i=0; i < nCount; i++)
{
int ri = r.Next(0,nlast+1);
int ntemp = indexlist[ri];
indexlist[ri] = indexlist[nlast];
indexlist[nlast] = ntemp;

nlast--;
}

//create a clone
dt2 = dt.Clone();

for (int i=0; i < nCount; i++)
{
dt2.ImportRow(dt.Rows[indexlist[indexlist.Length - i - 1]]);
}
}
else
dt2 = dt;

//bind your data to the datagrid
DataGrid1.DataSource = dt2.DefaultView;
....

[yuanylong]

学习并理解：
1）用Random()生成伪随机数。然后生成对应的行。先将行数存在数组中。然后在一个一个取出数据。在绑定表格。

[greystar]

select top 10 from urtable order by newid()
ok
随机取10题

[km168]

select top 10 * from yourtable .... order by NewID()

这么做不是取前10行吗?我需要随机取.

[saucer]

if you use "order by NewID()", the top 10 is always random