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c# - 如何按列格式化数据表行数据

问题描述

我在 c# 中有一个数据表，其中包含员工信息日期。下面是数据表数据。

 id   Name Salary  Hour     Date
---   ----- ------  -----   ------------------
1   Ram    10000.00 7.00    2018-11-01 00:00:00.000 1
1   Ram    10000.00 7.50    2018-11-02 00:00:00.000 2
2   Shyam   5000.00 8.50    2018-11-01 00:00:00.000 1
2   Shyam   5000.00 8.00    2018-11-02 00:00:00.000 2


I want the data table  result like below in c#

Name    2018-11-01  2018-11-02
------   ---------- ----------
Ram       7.00       7.50
Shyam     8.50       8.00

Can anybody help me on this?

Thanks

标签： c#asp.net.netlinqdatatable

解决方案

您可以尝试使用 linqgroup by和MAX

var query = myList
        .GroupBy(c => c.Name)
        .Select(g => new {
            Name = g.Key,
            _2018_11_01 = g.Where(c => c.Date == new DateTime(2018, 11, 1)).Max(c => c.Hour),
            _2018_11_02 = g.Where(c => c.Date == new DateTime(2018, 11, 2)).Max(c => c.Hour)
        });

如果要动态创建列，可以尝试在方法中编写 Lambda 表达式。

public static class ExtetionClass {
    public static DataTable ToPivotTable<T, TColumn, TRow, TData>(
       this IEnumerable<T> source,
       Func<T, TColumn> columnSelector,
       Expression<Func<T, TRow>> rowSelector,
       Func<IEnumerable<T>, TData> dataSelector)
    {
        DataTable table = new DataTable();
        var rowName = ((MemberExpression)rowSelector.Body).Member.Name;
        table.Columns.Add(new DataColumn(rowName));
        var columns = source.Select(columnSelector).Distinct();

        foreach (var column in columns)
            table.Columns.Add(new DataColumn(column.ToString()));

        var rows = source.GroupBy(rowSelector.Compile())
                         .Select(rowGroup => new
                         {
                             Key = rowGroup.Key,
                             Values = columns.GroupJoin(
                                 rowGroup,
                                 c => c,
                                 r => columnSelector(r),
                                 (c, columnGroup) => dataSelector(columnGroup))
                         });

        foreach (var row in rows)
        {
            var dataRow = table.NewRow();
            var items = row.Values.Cast<object>().ToList();
            items.Insert(0, row.Key);
            dataRow.ItemArray = items.ToArray();
            table.Rows.Add(dataRow);
        }

        return table;
    }

}

像这样使用

var pivotTable = myList.ToPivotTable(
          item => item.Date,
          item => item.Name,
          items => items.Any() ? items.Max(x => x.Hour) : 0);

foreach (DataRow rw in pivotTable.Rows)
{
    Console.WriteLine(string.Format("{0}   {1}   {2}", rw[0], rw[1], rw[2]));
}

c# 在线

Ram   7.0   7.5
Shyam   8.50   8.0

参考链接

使用 LINQ 将列转换为行

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