<t>You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable. You need to use the AsEnumerable() extension for DataTable. Like so:<br/>
<br/>
var results = from myRow in myDataTable.AsEnumerable()<br/>
where myRow.Field("RowNo") == 1<br/>
select myRow;<br/>
<br/>
```<br/>
<br/>
And as [@Keith](https://stackoverflow.com/a/10893/5519709) says, you'll need to add a reference to [System.Data.DataSetExtensions](http://msdn.microsoft.com/en-us/library/system.data.datarowextensions.aspx)<br/>
<br/>
`AsEnumerable()` returns `IEnumerable`. If you need to convert `IEnumerable` to a `DataTable`, use the `CopyToDataTable()` extension.<br/>
<br/>
Below is query with Lambda Expression,<br/>
<br/>
```<br/>
var result = myDataTable<br/>
.AsEnumerable()<br/>
.Where(myRow => myRow.Field("RowNo") == 1);<br/>
<br/>
```</t>
