Select distinct rows from datatable in Linq

问题

I am trying to get distinct rows based on multiple columns (attribute1_name, attribute2_name) and get datarows from datatable using Linq-to-Dataset.

I want results like this

attribute1_name    attribute2_name
--------------     ---------------

Age                State
Age                weekend_percent
Age                statebreaklaw
Age                Annual Sales
Age                Assortment

How to do thin Linq-to-dataset?

回答1:

If it's not a typed dataset, then you probably want to do something like this, using the Linq-to-DataSet extension methods:

var distinctValues = dsValues.AsEnumerable()
                        .Select(row => new {
                            attribute1_name = row.Field<string>("attribute1_name"),
                            attribute2_name = row.Field<string>("attribute2_name")
                         })
                        .Distinct();

Make sure you have a using System.Data; statement at the beginning of your code in order to enable the Linq-to-Dataset extension methods.

Hope this helps!

回答2:

Like this: (Assuming a typed dataset)

someTable.Select(r => new { r.attribute1_name, r.attribute2_name }).Distinct();

回答3:

var Test = (from row in Dataset1.Tables[0].AsEnumerable()
            select row.Field<string>("attribute1_name") + row.Field<int>("attribute2_name")).Distinct();

回答4:

Check this link

get distinct rows from datatable using Linq (distinct with mulitiple columns)

Or try this

var distinctRows = (from DataRow dRow in dTable.Rows
                    select new  {  col1=dRow["dataColumn1"],col2=dRow["dataColumn2"]}).Distinct();

EDIT: Placed the missing first curly brace.

回答5:

Dim distinctValues As List(Of Double) = (From r In _
DirectCast(DataTable.AsEnumerable(),IEnumerable(Of DataRow)) Where (Not r.IsNull("ColName")) _
Select r.Field(Of Double)("ColName")).Distinct().ToList()

回答6:

We can get the distinct similar to the example shown below

 //example
           var  distinctValues =  DetailedBreakDown_Table.AsEnumerable().Select(r => new
            {
                InvestmentVehicleID = r.Field<string>("InvestmentVehicleID"),
                Universe = r.Field<string>("Universe"),
                AsOfDate = _imqDate,
                Ticker = "",
                Cusip = "",
                PortfolioDate = r.Field<DateTime>("PortfolioDate")

            } ).Distinct();

来源：https://stackoverflow.com/questions/3242892/select-distinct-rows-from-datatable-in-linq

标签

vb.net

linq

linq-to-dataset