Windows linq

Add a closing parenthesis " " and press enter to execute the command. This example shows completion with a key comparator method. The substitution will show string methods, since the key is a string.

Length" appears. A user defined variable can be assigned to anything dx can utilize, for example, lambdas, the results of LINQ queries, etc. You can display the defined user variables using Debugger. This example create an anonymous type with an integer and string value. Many of the methods that are used to query data are based on the concept of repeatedly running a user provided function across objects in a collection. To support the ability to query and manipulate data in the debugger, the dx command supports lambda expressions using the equivalent C syntax.

Any object which dx defines as iterable be that a native array, a type which has NatVis written describing it as a container, or a debugger extension object has a series of LINQ or LINQ equivalent methods projected onto it. Those query methods are described below. The signatures of the arguments to the query methods are listed after all of the query methods. Where PredicateMethod : Returns a new collection of objects containing every object in the input collection for which the predicate method returned true.

Flatten [KeyProjectorMethod] : Takes an input container of containers a tree and flattens it into a single container which has every element in the tree. If the optional key projector method is supplied, the tree is considered a container of keys which are themselves containers and those keys are determined by a call to the projection method.

Select KeyProjectorMethod : Returns a new collection of objects containing the result of calling the projector method on every object in the input collection. GroupBy KeyProjectorMethod, [KeyComparatorMethod] : Returns a new collection of collections by grouping all objects in the input collection having the same key as determined by calling the key projector method.

An optional comparator method can be provided. Join InnerCollection, Outer key selector method, Inner key selector method, Result selector method, [ComparatorMethod] : Joins two sequences based on key selector functions and extracts pairs of values. An optional comparator method can also be specified. Intersect InnerCollection, [ComparatorMethod] : Returns the set intersection, which means elements that appear in each of two collections. Union InnerCollection, [ComparatorMethod] : Returns the set union, which means unique elements that appear in either of two collections.

Contains Object, [ComparatorMethod] : Determines whether a sequence contains a specified element. An optional comparator method can be provided that will be called each time the element is compared against an entry in the sequence. Distinct [ComparatorMethod] : Removes duplicate values from a collection. An optional comparator method can be provided to be called each time objects in the collection must be compared.

Except InnerCollection, [ComparatorMethod] : Returns the set difference, which means the elements of one collection that do not appear in a second collection. An optional comparator method can be specified.

OrderBy KeyProjectorMethod, [KeyComparatorMethod] : Sorts the collection in ascending order according to a key as provided by calling the key projection method on every object in the input collection. OrderByDescending KeyProjectorMethod, [KeyComparatorMethod] : Sorts the collection in descending order according to a key as provided by calling the key projection method on every object in the input collection.

Sum [ProjectionMethod] : Calculates the sum of the values in a collection. Can optionally specify a projector method to transform the elements before summation occurs. SkipWhile PredicateMethod : Skips elements based on a predicate function until an element does not satisfy the condition.

TakeWhile PredicateMethod : Takes elements based on a predicate function until an element does not satisfy the condition. SequenceEqual InnerCollection, [ComparatorMethod] : Determines whether two sequences are equal by comparing elements in a pair-wise manner.

An optional comparator can be specified. AllNonError PredicateMethod : Returns whether all non-error elements of a collection satisfy a given condition. All PredicateMethod : Returns whether the result of calling the specified predicate method on every element in the input collection is true.

Any PredicateMethod : Returns whether the result of calling the specified predicate method on any element in the input collection is true. First [PredicateMethod] : Returns the first element in the collection. LINQ support is also provided by third parties for many Web services and other database implementations. The following example shows the complete query operation. The complete operation includes creating a data source, defining the query expression, and executing the query in a foreach statement.

To learn more details about LINQ, start by becoming familiar with some basic concepts in Query expression basics , and then read the documentation for the LINQ technology in which you are interested:. Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Run new LinqToSql ;. The [Table] attribute marks the class as an entity class and has an optional Name property that can be used to provide the name of a table, that defaults to the class name.

That's why you name the class Contact rather than Person. The [Column] attribute marks a field as one that will hold data from a table. You can declare fields in an entity class that don't map to table columns, and LINQ will just ignore them, but those decorated with the [Column] attribute must be of types compatible with the table columns they map to. Note that since SQL Server table and column names aren't case sensitive, the default names do not need to be identical in case to the names used in the database.

NET connection does, but it also does things that a data provider handles. The GetTable method of the DataContext class tells the data context to access the results and indicates where to put them. Here, you get all the rows but only three columns from the Person. Contact table, and the data context creates an object for each row in the contacts typed table.

You initialize the local variable with a query expression as in the following: from c in contacts where c. FirstName select c; A query expression is composed of a from clause and a query body. The from clause declares an iteration variable, c, to be used to iterate over the result of the expression, contacts, that is, over the typed table you earlier created and loaded.

In other words Title must be "Mr. Finally, you loop through the custs collection and display each customer. Except for the use of the var type, that was introduced as a new data type in C and continue to exist in advance versions like C Once you get the hang of it, it's an appealing alternative for coding queries.

You basically code a query expression instead of SQL to populate a collection that you can iterate through with a foreach statement.

However, you provide a connection string, but don't explicitly open or close a connection. Further, no command, data reader, or indexer is required. You don't even need the System. Data or System. Pretty cool, isn't it? Drag a Text Box control onto the form, and position it towards the center of the form.

Add the code shown in Listing in "LinqToXml. Descendants "products" select prodname. AppendText prodname ; txtLinqToXml. Run new LinqToSql ; to appear as: Application. Run new LinqToXml ;. View All.

Vidya Vrat Agarwal Updated date Sep 21, LINQ introduces a standard, unified, easy-to-learn approach for querying and modifying data, and can be extended to support potentially any type of data store. LINQ offers the following advantages:.