Datatable select with multiple conditions

Yes, the DataTable.Select method supports boolean operators in the same way that you would use them in a "real" SQL statement:

DataRow[] results = table.Select("A = 'foo' AND B = 'bar' AND C = 'baz'");

See DataColumn.Expression in MSDN for the syntax supported by DataTable's Select method.

Do you have to use DataTable.Select()? I prefer to write a linq query for this kind of thing.

var dValue=  from row in myDataTable.AsEnumerable()
             where row.Field<int>("A") == 1 
                   && row.Field<int>("B") == 2 
                   && row.Field<int>("C") == 3
             select row.Field<string>("D");

I found that having too many and's would return incorrect results (for .NET 1.1 anyway)

DataRow[] results = table.Select("A = 'foo' AND B = 'bar' AND C = 'baz' and D ='fred' and E = 'marg'"); 

In my case A was the 12th field in a table and the select was effectively ignoring it.

However if I did

DataRow[] results = table.Select("A = 'foo' AND (B = 'bar' AND C = 'baz' and D ='fred' and E = 'marg')"); 

The filter worked correctly!