Professional LINQ

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Scott Klein

"Professional LINQ"

FirstName).ToList();
76
Chapter 4: LINQ Standard Query Operators
foreach (string item in query)
listBox1.Items.Add(item);
ToLookup
The ToLookup operator puts the returned elements into a Lookup(Of Tkey, TElement), based on a speci-
fied key. A Lookup is a collection of keys, each of which is mapped to one or more values; you can think
of it as a one-to-many dictionary.
The following example uses the ToLookup operator to create and populate a Lookup(Of TKey,
TElement)and then iterate through that Lookup to populate a list box.
DataContext context = new DataContext("Initial Catalog =
AdventureWorks;Integrated Security=sspi");
Table contact = context.GetTable();
Lookup lkp = contact.ToLookup(con => con.FirstName,
con => con.MiddleName + " " + con.LastName);
foreach (IGrouping lkpgrp in lkp)
{
listBox1.Items.Add(lkpgrp.Key);
foreach (string item in lkpgrp)
listBox1.Items.Add(" " + item);
}
In this example, a Lookup is created, and contacts??™ first, middle, and last names are used to populate the
Lookup, using the contact??™s last name as a key.

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An Account of the Customs and Manners of the Micmakis and Maricheets Savage Nations, Now Dependent on the Government of Cape-Breton (page 70) Danny's Own Story (page 288) Mrs. Falchion, Volume 2. (page 143)

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Scott Klein

"Professional LINQ"