Data Table Group by in Linq

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Consider I have data table with two columns,

C#

1. ItemID --> String data type
2. Items --> Decimal data type

I want to find Total Items Per ItemID. But my column and data type may change. So please
give suggestions on following syntax

C#

var query = from row in dt.AsEnumerable()
                                     group row by row.Field<String>(0) into grp
                                     select new
                                     {
                                         ItemID = grp.Key,
                                         TotalItems = grp.Sum(r => r.Field<Decimal>(2))
                                     };

In above syntax, instead of passing <String>, I want to pass data type dynamically depending on datatype of column.

Posted 7-Mar-14 3:02am

Member 4373780

Updated 7-Mar-14 3:16am

Sampath Lokuge

v2

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Anand Gunasekaran · Answer 1 · 2014-03-07T06:19:00

Solution 1

use dynamic type.

C#

var query = from row in dt.AsEnumerable()
                                     group row by row.Field<dynamic>(0) into grp
                                     select new
                                     {
                                         ItemID = grp.Key,
                                         TotalItems = grp.Sum(r => r.Field<Decimal>(2))
                                     };

Dynmic type is bypass the data type checking so you case dynamically get the results from the above query.

Ref. : Using Type dynamic[^]

Posted 7-Mar-14 6:19am

Anand Gunasekaran

Comments

Maciej Los 7-Mar-14 13:15pm

+5!

Member 4373780 11-Mar-14 9:08am

You are right but I want to store those values using following,
foreach (var grp in query)
{
DataRow dr = dtMainChartData.NewRow();
dr["KeyColumn"] = grp.KeyColumn;
dr["Total"] = grp.Total;
dtMainChartData.Rows.Add(dr);
}

Here how can I set data type of data type of data column as dynamic. Here I have set data type of data column accordingly Data type of SQL in runtime like,

KeyColumnDataType = dtDrillDownChartData.Columns[0].DataType.FullName;
TotalDataType = dtDrillDownChartData.Columns[2].DataType.FullName;

dtMainChartData.Columns.Add("KeyColumn", System.Type.GetType(KeyColumnDataType));
dtMainChartData.Columns.Add("Total", System.Type.GetType(TotalDataType));

Anand Gunasekaran 11-Mar-14 13:59pm

Hi, I changed the mentioned code that you have posted. Here you check the code.

foreach (var grp in query)
{
DataRow dr = dtMainChartData.NewRow();
dr["KeyColumn"] = grp.ItemID[0];
dr["Total"] = grp.ItemID[2];
dtMainChartData.Rows.Add(dr);
}

dtMainChartData.Columns.Add("KeyColumn", System.Type.GetType(dtDrillDownChartData.Columns[0].DataType.FullName));
dtMainChartData.Columns.Add("Total", System.Type.GetType(dtDrillDownChartData.Columns[2].DataType.FullName));

Thanks & Regards,
Anand. G