Why Field is required for DataTable Linq

Here is one good blog for the same Click here

E.g

DataTable dt = new DataTable();

//Adding Columns and names
dt.Columns.Add("ID" ,typeof(int));
dt.Columns.Add("Name",typeof(string));

//Adding Rows and values

dt.Rows.Add(1,"anish");
dt.Rows.Add(2,"marokey");
dt.Rows.Add(2,"varghese");

//querying the result where ID is 2
var result = from p in dt.AsEnumerable()
where p.Field("ID") == 2
select p.Field("Name");

Add Columns and Name to DataTable

Here is a simple example to add values to DataTable

DataTable dt = new DataTable();

//Adding Columns and names
dt.Columns.Add("ID" ,typeof(int));
dt.Columns.Add("Name",typeof(string));

//Adding Rows and values

dt.Rows.Add(1,"anish");
dt.Rows.Add(2,"marokey");

What are the DataColumn.Expression property and what are the errors can cause in DataColumn.Expression

http://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression.aspx