private void Form1_Load(object sender, EventArgs e)
{
#region 
DataTable dt = new DataTable();
dt.Columns.Add("name");
dt.Columns.Add("name2");
dt.Columns.Add("type");
dt.Columns.Add("count");

Random ran3 = new Random();
Random ran = new Random();
Random ran2 = new Random();

Stopwatch stopWatch = new Stopwatch();
stopWatch.Start();
DataRow dr ;
for (int i = 0; i < 50000; i++)
{
int k3 = ran3.Next(1, 2000);
int k=ran.Next(1, 13);
int c=ran2.Next(50, 100);

dr = dt.NewRow();

dr["name"] = "n"+k3.ToString();
dr["name2"] = "n2" + k3.ToString();
dr["type"] = "t"+k.ToString();
dr["count"] = "co"+c.ToString();
dt.Rows.Add(dr);
}
stopWatch.Stop();
Console.WriteLine(stopWatch.ElapsedMilliseconds.ToString());

#endregion
stopWatch.Restart();
DataTable dt2=getDt(dt, "type", "count","name","name2");
stopWatch.Stop();
Console.WriteLine(stopWatch.ElapsedMilliseconds.ToString());
this.dataGridView1.DataSource = dt2;
}
/// <summary>
///
/// </summary>
/// <param name="dtsource">数据源</param>
/// <param name="colName">需要转置为列名的列 如city列</param>
/// <param name="dataName">需要转置的数据列 如count列</param>
/// <param name="val">其他可区分列 如name2列</param>
/// <returns></returns>
DataTable getDt(DataTable dtsource, string colName, string dataName, params string[] fileds)
{
DataTable dt = new DataTable();

DataTable newTable = dtsource.DefaultView.ToTable(true, fileds);

DataTable dtcol = dtsource.DefaultView.ToTable(true, colName);

foreach (DataRow item in dtcol.Rows)
{
newTable.Columns.Add(item[0].ToString());
}

for (int i = 0; i < newTable.Rows.Count; i++)
{
string strSel1 = "1=1 ";
for (int k = 0; k < fileds.Length; k++)//处理开头的数据
{
string rowname = newTable.Rows[i][k].ToString();
newTable.Rows[i][k] = rowname;
strSel1 += string.Format(" and {0}='{1}'",fileds[k],rowname);
}

for (int j = fileds.Length; j < newTable.Columns.Count; j++)
{
string cname = newTable.Columns[j].ColumnName;

string strSel2 = string.Format("{0}='{1}'",colName,cname);

DataRow[] dn = dtsource.Select(strSel1 + " and " + strSel2);

if (dn!=null&&dn.Length>0)
{
newTable.Rows[i][j] = dn[0][dataName].ToString();
}
}
}

return newTable;
}