how to join 3 datatable using linq in c#

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Hello,
I have three data table (t1,t2,t3) in frontened i want to join this tables to make a single table how to do this using linq query ....

I am using this but it doesn't work and also i want to show output in datatable form to perform other action

C#

var query = from a in t1
            join b in t2 on a.someFieldID equals b.someFieldID
             join c in t3 on b.someFieldID equals c.someFieldID
            select a;

Thanks and regards
Srishti

Posted 31-Aug-14 20:35pm

srishti_

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2 solutions

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

harshavardhan12345678 · Accepted Answer · 2014-08-31T20:43:00

C#

DataTable dtResult = new DataTable();
dtResult.Columns.Add("ID", typeof(string));
dtResult.Columns.Add("name", typeof(string));
dtResult.Columns.Add("stock", typeof(int));

var result = from dataRows1 in table1.AsEnumerable()
             join dataRows2 in table2.AsEnumerable()
             on dataRows1.Field<string>("ID") equals dataRows2.Field<string>("ID")

             select dtResult.LoadDataRow(new object[]
             {
                dataRows1.Field<string>("ID"),
                dataRows1.Field<string>("name"),
                dataRows2.Field<int>("stock"),
              }, false);
result.CopyToDataTable();

Code originally written by Sven Grosen: http://stackoverflow.com/a/20760794[^]

sankarsan parida · Accepted Answer · 2014-08-31T20:50:00

Solution 2

if you are using datatable for that you have to use AsEnumerable() method for linq
And your query should be like below you can change your FKey relationship

var query = (from a in t1.AsEnumerable()
                     join b in t2.AsEnumerable() on a.Field<int>("id") equals b.Field<int>("fkey")
                     join c in t3.AsEnumerable() on b.Field<int>("id") equals c.Field<int>("fkey")
                     select a).ToList();
        //If You are selecting a single table then you can convert to table on the following way
        if (query.Count > 0)
        {
            DataTable newDt = query.CopyToDataTable();
        }

Get More info HERE[^]

Posted 31-Aug-14 20:50pm

sankarsan parida

Updated 31-Aug-14 21:10pm

v2

Comments

srishti_ 1-Sep-14 3:01am

thanks but how to convert in into datatable

[no name] 1-Sep-14 3:11am

welcome
see again updated solution not exact but the idea is like this

harshavardhan12345678 1-Sep-14 3:17am

you can use this extension method and call it like this.

public static DataTable ToDataTable<t>(List<t> items)
{
DataTable dataTable = new DataTable(typeof(T).Name);

//Get all the properties
PropertyInfo[] Props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
foreach (PropertyInfo prop in Props)
{
//Setting column names as Property names
dataTable.Columns.Add(prop.Name);
}
foreach (T item in items)
{
var values = new object[Props.Length];
for (int i = 0; i < Props.Length; i++)
{
//inserting property values to datatable rows
values[i] = Props[i].GetValue(item, null);
}
dataTable.Rows.Add(values);
}
//put a breakpoint here and check datatable
return dataTable;
}

how to join 3 datatable using linq in c#

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how to join 3 datatable using linq in c#

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