Professional LINQ

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Scott Klein

"Professional LINQ"

GetTable();
var query = orders.Where(ord => ord.SalesPersonID > 0).GroupBy(order =>
order.SalesPersonID,
order => order.CustomerID);
foreach (var o in query)
{
listBox1.Items.Add(o.Key);
foreach (int cust in o)
listBox1.Items.Add(" " + cust);
}
It can also be written as follows (given the same DataContext and table):
IEnumerable> query = orders.Where(ord =>
ord.SalesPersonID > 0).GroupBy(order => order.SalesPersonID, order =>
order.CustomerID);
62
Chapter 4: LINQ Standard Query Operators
foreach (IGrouping o in query)
{
listBox1.Items.Add(o.Key);
foreach (int cust in o)
listBox1.Items.Add(" " + cust);
}
Here are the results:
268
697
47
471
548
167
...
275
504
618
17
486
269
276
510
511
259
384
650
...
The first example could also be written using a mix of query syntax and method syntax as follows:
var query =
(from o in orders
where o.SalesPersonID > 0
select o).GroupBy(order => order.SalesPersonID,
order => order.CustomerID);
This makes the query somewhat easier to read, even though the example used a mix of the two
syntaxes.

Pages:
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Scott Klein

"Professional LINQ"