How to select distinct rows in a datatable and store into an array

Question

DataView view = new DataView(table);
DataTable distinctValues = view.ToTable(true, "Column1", "Column2" ...);

Following single line of code will avoid the duplicate rows of a DataTable:

dataTable.DefaultView.ToTable(true, "employeeid");

Where:

• first parameter in ToTable() is a boolean which indicates whether you want distinct rows or not.

• second parameter in the ToTable() is the column name based on which we have to select distinct rows. Only these columns will be in the returned datatable.

The same can be done from a DataSet, by accessing a specific DataTable:

dataSet.Tables["Employee"].DefaultView.ToTable(true, "employeeid");

DataTable dt = new DataTable();
dt.Columns.Add("IntValue", typeof(int));
dt.Columns.Add("StringValue", typeof(string));
dt.Rows.Add(1, "1");
dt.Rows.Add(1, "1");
dt.Rows.Add(1, "1");
dt.Rows.Add(2, "2");
dt.Rows.Add(2, "2");

var x = (from r in dt.AsEnumerable()
        select r["IntValue"]).Distinct().ToList();

With LINQ (.NET 3.5, C# 3)

var distinctNames = ( from row in DataTable.AsEnumerable()
 select row.Field<string>("Name")).Distinct();

 foreach (var name in distinctNames ) { Console.WriteLine(name); }

You can use like that:

data is DataTable

data.DefaultView.ToTable(true, "Id", "Name", "Role", "DC1", "DC2", "DC3", "DC4", "DC5", "DC6", "DC7");  

but performance will be down. try to use below code:

data.AsEnumerable().Distinct(System.Data.DataRowComparer.Default).ToList();  

For Performance ; http://onerkaya.blogspot.com/2013/01/distinct-dataviewtotable-vs-linq.html

var distinctRows = (from DataRow dRow in dtInventory.Rows
                                select dRow["column_name"] ).Distinct();

var distinctRows = (from DataRow dRow in dtInventory.Rows
                                select dRow["col1"], dRow["col2"].. ).Distinct();

To improve the above answer: The ToTable function on dataview has a "distinct" flag.

//This will filter all records to be distinct
dt = dt.DefaultView.ToTable(true);