我有一个DataTable，想要对Name，LastName和Comment进行分组。其余的应该在同一行。 在我的代码中，我首先将ID的值作为标题，然后将Attribute值组织到每个ID。我想要的是将相同的名称，姓氏和注释与其ID值分组。 我的第一张表看起来像这样：
ID Name Lastmame Comment Attribute
1 kiki ha hello FF
3 lola mi hi AA
2 ka xe what UU
2 kiki ha hello SS
使用我的代码后：
Name Lastname Comment 1 3 2
kiki ha hello FF
lola mi hi AA
ka xe what UU
kiki ha hello SS
我想要的是：
Name Lastname Comment 1 3 2
kiki ha hello FF SS
lola mi hi AA
ka xe what UU
我的代码：
DataTable table1 = new DataTable("Kunde");
table1.Columns.Add("Comment", typeof(String));
table1.Columns.Add("Name", typeof(String));
table1.Columns.Add("Lastname", typeof(String));
DataTable comment = new DataTable("Comment");
comment.Columns.Add("ID", typeof(String));
comment.Columns.Add("Comment", typeof(String));
comment.Columns.Add("Attribute", typeof(String));
DataSet ds = new DataSet("DataSet");
ds.Tables.Add(table1);
ds.Tables.Add(comment);
object[] o1 = { "hello", "kiki", "ha" };
object[] o2 = { "hi", "lola", "mi" };
object[] o3 = { "what", "ka", "xe" };
object[] c1 = { 1, "hello", "FF" };
object[] c2 = { 3, "hi", "AA" };
object[] c3 = { 2, "what", "UU" };
object[] c4 = { 2, "hello", "SS" };
table1.Rows.Add(o1);
table1.Rows.Add(o2);
table1.Rows.Add(o3);
comment.Rows.Add(c1);
comment.Rows.Add(c2);
comment.Rows.Add(c3);
comment.Rows.Add(c4);
var results = from tb1 in comment.AsEnumerable()
join tb2 in table1.AsEnumerable()
on tb1.Field<string>("Comment") equals tb2.Field<string>("Comment")
select new
{
ID = tb1.Field<String>("ID"),
Name = tb2.Field<String>("Name"),
Lastname = tb2.Field<String>("Lastname"),
Comment = tb1.Field<String>("Comment"),
Attribute = tb1.Field<String>("Attribute"),
};
DataTable result = LINQToDataTable(results);
var products = result.AsEnumerable()
.GroupBy(c => c["ID"])
.Where(g => !(g.Key is DBNull))
.Select(g => (string)g.Key)
.ToList();
var newtable = result.Copy();
products.ForEach(p => newtable.Columns.Add(p, typeof(string)));
foreach (var row in newtable.AsEnumerable())
{
if (!(row["ID"] is DBNull)) row[(string)row["ID"]] = row["Attribute"];
}
newtable.Columns.Remove("ID");
newtable.Columns.Remove("Attribute");
var result11 = from t1 in newtable.AsEnumerable()
group t1 by new { Name = t1.Field<String>("Name"), LastName = t1.Field<String>("LastName"), Comment = t1.Field<String>("Comment"), } into grp
select new
{
Name = grp.Key.Name,
LastName = grp.Key.LastName,
Comment = grp.Key.Comment,
//Something here
};
LINQToDataTable方法定义
using System.Reflection;
public DataTable LINQToDataTable<T>(IEnumerable<T> varlist)
{
DataTable dtReturn = new DataTable();
// column names
PropertyInfo[] oProps = null;
if (varlist == null) return dtReturn;
foreach (T rec in varlist)
{
if (oProps == null)
{
oProps = ((Type)rec.GetType()).GetProperties();
foreach (PropertyInfo pi in oProps)
{
Type colType = pi.PropertyType;
if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition()
== typeof(Nullable<>)))
{
colType = colType.GetGenericArguments()[0];
}
dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
}
}
DataRow dr = dtReturn.NewRow();
foreach (PropertyInfo pi in oProps)
{
dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue
(rec, null);
}
dtReturn.Rows.Add(dr);
}
return dtReturn;
}
答案 0 :(得分：1)
根据对this other answer的评论：
一种方法是将所有变量列填充到结构中（如字典）。
要执行此操作，请使用以下查询：
var variableColumnNames = newtable.Columns.Cast<DataColumn>()
.Select(c => c.ColumnName)
.Except(new[]{"Name", "Lastname", "Comment"});
var result11 = from t1 in newtable.AsEnumerable()
group t1 by new
{
Name = t1.Field<String>("Name"),
LastName = t1.Field<String>("LastName"),
Comment = t1.Field<String>("Comment"),
} into grp
select new
{
grp.Key.Name,
grp.Key.LastName,
grp.Key.Comment,
Values = variableColumnNames.ToDictionary(
columnName => columnName,
columnName => grp.Max(r => r.Field<String>(columnName)))
};
如果你真的需要在类中有可变数量的属性，据我所知这是不可能的，所以唯一可行的方法是将结果输出到另一个DataTable（到我们可以添加尽可能多的列。
dynamic LINQ查询：
var result11 = from t1 in newtable.AsEnumerable()
group t1 by new
{
Name = t1.Field<String>("Name"),
LastName = t1.Field<String>("LastName"),
Comment = t1.Field<String>("Comment"),
} into grp
select CreateNewDynamicObject
(
grp.Key.Name,
grp.Key.LastName,
grp.Key.Comment,
variableColumnNames.ToDictionary(
columnName => columnName,
columnName => grp.Max(r => r.Field<String>(columnName)))
);
}
创建动态对象的新方法：
private static dynamic CreateNewDynamicObject(
string name, string lastName, string comment, Dictionary<string, string> customProperties)
{
dynamic obj = new ExpandoObject();
obj.Name = name;
obj.LastName = lastName;
obj.Comment = comment;
foreach (var prop in customProperties)
(obj as IDictionary<string, Object>).Add(prop.Key, prop.Value ?? "");
return obj;
}
DataTable 结果DataTable（destinationTable）可用作DataGridView的来源：
var destinationTable = new DataTable();
foreach (var column in newtable.Columns.Cast<DataColumn>())
destinationTable.Columns.Add(column.ColumnName, typeof(String));
var result11 =
from t1 in newtable.AsEnumerable()
group t1 by new
{
Name = t1.Field<String>("Name"),
LastName = t1.Field<String>("Lastname"),
Comment = t1.Field<String>("Comment"),
}
into grp
select
variableColumnNames.ToDictionary(
columnName => columnName,
columnName => grp.Max(r => r.Field<String>(columnName)))
.Concat(new Dictionary<string, string>
{
{"Name", grp.Key.Name},
{"Lastname", grp.Key.LastName},
{"Comment", grp.Key.Comment}
}
).ToDictionary(x => x.Key, x => x.Value);
foreach (var row in result11)
{
var newRow = destinationTable.NewRow();
foreach (var columnName in newtable.Columns.Cast<DataColumn>().Select(c => c.ColumnName))
newRow[columnName] = row[columnName];
destinationTable.Rows.Add(newRow);
}