Figure 1-5 shows the output. Listing 2-23 shows the code necessary to execute this method and retrieve the total money amount for the year 2004. Write query ; This code snippet uses the method without the seed parameter, so it takes the first element, 1, as seed, multiplying it for each other element in the sequence. The DataContext class uses the connection string to discover whether the database already exists. Figure 3-17 shows the output of the code snippet in Listing 3-27. If no element is found, a false value is returned.
If all of them satisfy the predicate condition then a true value is returned. See Figure 1-22 for the resulting output. Listing 1-11 shows these classes. From Server Explorer select the Connect to Database button, as shown in Figure 2-19. The Right property provides the right part of the expression, 1. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. For example, a table containing a list of orders could have a foreign key pointing to a customers table.
The RemoveContent method applied to the first role element RemoveAttribute called on the current element removes all its attributes. You could use code like that in Listing 1-4 to obtain the same result, but the lambda expression syntax is simpler. Figure 3-5 shows the output of this code snippet. In Listing 1-49 the Intersect method compares two numeric sequences and returns the common elements: 1 and 3. Lead Editor: James Huddleston Technical Reviewer: Vidya Vrat Agarwal Editorial Board: Steve Anglin, Ewan Buckingham, Gary Cornell, Jason Gilmore, Jonathan Gennick, Jonathan Hassell, James Huddleston, Chris Mills, Matthew Moodie, Dominic Shakeshaft, Jim Sumser, Keir Thomas, Matt Wade Project Manager: Kylie Johnston Copy Edit Manager: Nicole Flores Copy Editor: Candace English Assistant Production Director: Kari Brooks-Copony Compositor: Richard Ables Cover Designer: Kurt Krames Manufacturing Director: Tom Debolski Distributed to the book trade worldwide by Springer-Verlag New York, Inc. Write query ; Figure 1-7. We have defined a way to group fruit with fruit and thing with thing.
It also details significant enhancements to C ,. Complete ; } We can test the pessimistic concurrency by executing two separate application instances like in Listing 2-13. The Join operator is not overloaded. The from clause specifies a data source. This file contains the source code for all the extension methods in the System.
However, nothing happens in the database until you call the SubmitChanges method shown in Listing 2-5. The code snippet in Listing 1-12 uses Where through the C where keyword to retrieve every element in a sequence that has FirstName equal to Brad. On the other hand, the LastOrDefault operator looks for the last odd number in the sequence and finds the number 9. We can also modify the query. You can search for a particular attribute in a similar way. This could be useful to call a standard query expression when a type implements its own queryexpression methods. ThisKey Identifies a list of keys of this entity class, separated by commas.
So just before the Compare method is called in the comparer function, we will remove each underscore from the source strings. We can search for all the comments as in Listing 3-7. When seed is specified the operator uses the seed value as a starting point for applying the aggregate function. As the output in Figure 1-4 shows, even if the code changes an element of the List collection, the query returns the same result since it has been cached. OfType ; Cast This operator casts the elements of the sequence to a given type. The OrderByDescending operator inverts the ordering. Concat This operator concatenates two sequences.
In Listing 3-10 the code searches for the default font style used in the Word document. The Attribute method returns the value of the attribute whose name is specified as its argument. The difference between the null and zero value depends on the source type: null for reference types i. The output for Listing 1-33 SkipWhile The SkipWhile operator skips elements from a sequence while the predicate function returns true, then it yields the rest. The first prototype without the selector parameter computes the sum of the elements in the sequence.
To run the code examples, you must create the People database first. In Listing 1-37 just one element 9 satisfies the predicate condition that the elements must be greater than 8. The output for Listing 1-23 To obtain descending order, you simply add the descending keyword. The Role table is transformed into the Region entity class after dragging and dropping the table from Server Explorer. Column-Attribute Properties Property Description AutoGen Identifies a column whose value is generated by the database. Listing 1-29 shows the operator in action.
The code in Listing 2-10 retrieves a single Person object and then uses its role. You can use the SelfAndDescendants and SelfAndAncestors methods to include the current node. Range 1, 10 ; Repeat This operator produces a sequence by repeating a value a given number of times. KeepCurrentValues: This rolls back each change made by the other client to the original database state. Standalone ; Figure 3-7 shows the output of Listing 3-15. Listing 2-7 shows the code.
After the Enter key is pressed the SkipWhile method is used with the same predicate condition to yield the other elements. From the Add Connection dialog box shown in Figure 2-20 you specify every parameter—server name, database, and so on—to connect to a database. The contract subordinated by this interface forces us to implement two methods: Equals and GetHashCode. ContinueOnConflict the OptimisticConcurrencyException is filled with some attributes that we can use to personalize the way optimistic concurrency is managed. GetTable ; create a data context, PeopleDataContext, and a Table collection, People for the Person database table , available in that context. Linq For Visual C 2005 Ferracchiati Fabio Claudio can be very useful guide, and linq for visual c 2005 ferracchiati fabio claudio play an important role in your products. DefaultIfEmpty This operator replaces an empty element with a default element in a sequence, as in the following examples.