从数据表中随机选取一条记录

Question

I'm trying to create an application which import an excel file and read the data from it and it returns n records randomly as winners according to how many winners the user want from that list. so i read the data from excel file and assign it to a datatable called dt . here is a small overview

thats the first 30 records in the excel which will be imported to dt . now if user key in 10(thats the total number of winners), i need to pick 10 winners "RANDOMLY" from this dt , but as you can see some of them are duplicated for example: in column D, the entry named "H" has 6 rows. now if the application chose 1 of them, the others "H" have to be removed but that is after it has been chosen. removing the duplicates before choosing any of them, will lower the chance for them to win better prizes.

Answer 1

Could you try something like,

dt2 = dt.Clone();
dt.AsEnumerable().Select(x => x["IC_NUMBER"].ToString()).Distinct().ToList().ForEach(x =>
{
    DataRow[] dr = dt.Select("IC_NUMBER = '" + x + "'");
    dt2.ImportRow(dr[0]);
    dr.ToList().ForEach(y => dt.Rows.Remove(y));
    dt.AcceptChanges();
});

EDIT:

int totalWinners = 10;
Random rnd = new Random();
dt2 = dt.Clone();
for (int i = 1; i <= totalWinners; i++)
{
    //Pick random datarow
    DataRow selectedWinner = dt.Rows[rnd.Next(0, dt.Rows.Count - 1)];
    //Insert it in the second table
    dt2.ImportRow(selectedWinner);
    //Retrieve other datarows that have same 'IC NUMBER'
    var rows = dt.AsEnumerable().Where(x => x["IC NUMBER"].ToString() ==
                                            selectedWinner["IC NUMBER"].ToString());
    //Delete all the rows with the selected IC NUMBER in the first table
    rows.ToList().ForEach(y => dt.Rows.Remove(y));
    dt.AcceptChanges();
}

Hope this helps...