Question

我有一个查询，只是想按ticketStatus =出席，然后发出，然后未付款，然后取消的顺序订购。谢谢

#include<stdio.h> 
int main()
{
    int a = a;
    printf ("%d",a);
    return 0;
}

Answer 1

按照@mjwills答案的建议，创建一个枚举。但是！

您无法对数据表See this answer进行就地排序。

因此，请按照以下两个步骤对数据表进行排序。

创建一个枚举

枚举TicketStatuss { 出席= 1，已发出= 2 未付= 3，已取消= 4 }

我尝试了VS2017和.Net Core 2中的以下代码，并根据您的要求进行了正确排序。

class Program
{
    static void Main(string[] args)
    {
        DataTable dt = new DataTable();
        DataColumn dc = new DataColumn("id", typeof(String));
        dt.Columns.Add(dc);

        dc = new DataColumn("TicketStatus", typeof(TicketStatuses));
        dt.Columns.Add(dc);

        DataRow dr;
        //Adding test data of 6 rows
        for (int i = 0; i <= 6; i++)
        {
            dr = dt.NewRow();

            dr[0] = i + 2; //Just a random column value - Could be anything here.
            dt.Rows.Add(dr);
        }
        // Setting column values for Column "TicketStatus" of our choice.
        dt.Rows[0][1] = TicketStatuses.Unpaid;
        dt.Rows[1][1] = TicketStatuses.Cancelled;
        dt.Rows[2][1] = TicketStatuses.Cancelled;
        dt.Rows[3][1] = TicketStatuses.Issued;
        dt.Rows[4][1] = TicketStatuses.Attended;
        dt.Rows[5][1] = TicketStatuses.Attended;
        dt.Rows[6][1] = TicketStatuses.Issued;

        //sorting datarows
        DataRow[] dataRows = dt.Select().OrderBy(u => u["TicketStatus"]).ToArray();

        DataTable sortedDatatable = dataRows.CopyToDataTable();
    }
}

干杯！

Answer 2

您可以使用自定义比较器（但是我想使用枚举会更好）。另外，如果您的OrderBy应该转换为SQL查询，则不能使用此比较器。

示例：

public class TicketStatusComparer : IComparer<string>
{
    private int GetIntValue( string value )
    {
        switch ( value )
        {
            case "Attended":
                return 1;
            case "Issue":
                return 2;
            case "Unpaid":
                return 3;
        }

        return 0;
    }

    public int Compare( string x, string y )
    {
        return GetIntValue( x ) - GetIntValue( y );
    }
}

然后像这样使用它：

var list = new[]
{
    new { A = 1, TicketStatus = "Issue" },
    new { A = 2, TicketStatus = "Attended" },
    new { A = 3, TicketStatus = "Unpaid" },
    new { A = 4, TicketStatus = "Attended" },
    new { A = 5, TicketStatus = "Unpaid" },
};

var xxx = list.OrderBy( x => x.TicketStatus, new TicketStatusComparer() ).ToList();

Answer 3

我刚刚发现我可以使用条件

       .OrderBy(x => x["TicketStatus"].ToString())
        .ThenBy(x => x["TicketStatus"].ToString() == "Attended")
        .ThenBy(x => x["TicketStatus"].ToString() == "Issued")
        .ThenBy(x => x["TicketStatus"].ToString() == "Unpaid")
        .ThenBy(x => x["TicketStatus"].ToString() == "Cancelled")

C＃lambda linq按多列索引排序

3 个答案: