Vikram Lakhotia Blog on Asp.Net, Dot Net, SQL, VIsual Studio, C# etc

LINQ also provides with itself important aggregate function. Aggregate function are function that are applied over a sequence like and return only one value like Average, count, sum, Maximum etc…
Below are some of the Aggregate functions provided with LINQ and example of their implementation.

Count

    int[] primeFactorsOf300 = { 2, 2, 3, 5, 5 };

    int uniqueFactors = primeFactorsOf300.Distinct().Count();

The below example provided count for only odd number.

While working with data most of the time we have to work with relation between different lists of data. Many a times we want to fetch data from both the list at once. This requires us to make different kind of joins between the lists of data.

LINQ support different kinds of join

Inner Join

    List<Customer> customers = GetCustomerList();

    List<Supplier> suppliers = GetSupplierList();

Visual studio 2010 has been released to RTM a few days back. This release of Visual studio 2010 comes with a big number of improvements on many fronts. In this post I will try and point out some of the major improvements in Visual Studio 2010.

1)      Visual studio IDE Improvement. Visual studio IDE has been rewritten in WPF. The look and feel of the studio has been improved for improved readability. Start page has been redesigned and template so that anyone can change the start page as they wish.

Many of the times while doing the performance tuning of some, class, webpage, component, control etc. we first measure the current time taken in the execution of that code. This helps in understanding the location in code which is actually causing the performance issue and also help in measuring the amount of improvement by making the changes.

This measurement is very important as it helps us understand the problem in code, Helps us to write better code next time (as we have already learnt what kind of improvement can be made with different code) .

LINQ is also very useful when it comes to generation of range or repetition of data.  We can generate a range of data with the help of the range method.

    var numbers =

        from n in Enumerable.Range(100, 50)

        select new {Number = n, OddEven = n % 2 == 1 ? "odd" : "even"};

While working with data it’s not always required that we fetch all the records. Many a times we only need to fetch the first record, or some records in some index, in the record set. With LINQ we can get the desired record very easily with the help of the provided element operators.

Simple get the first record.

If you want only the first record in record set we can use the first method [Note that this can also be done easily done with the help of the take method by providing the value as one].

    List<Product> products = GetProductList();

LINQ has a habit of returning things as IEnumerable. But we have all been working with so many other format of lists like array ilist, dictionary etc that most of the time after having the result set we want to get them converted to one of our known format. For this reason LINQ has come up with helper method which can convert the result set in the desired format. Below is an example

var sortedDoubles =

        from d in doubles

        orderby d descending

There are many set operation that are required to be performed while working with any kind of data. This can be done very easily with the help of LINQ methods available for this functionality. Below are some of the examples of the set operation with LINQ.

Finding distinct values in the set of data.

We can use the distinct method to find out distinct values in a given list.

    int[] factorsOf300 = { 2, 2, 3, 5, 5 };

While working with any kind of advanced query grouping is a very important factor. Grouping helps in executing special function like sum, max average etc to be performed on certain groups of data inside the date result set. Grouping is done with the help of the Group method. Below is an example of the basic group functionality.

    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    var numberGroups =

After filtering and retrieving the records most of the time (if not always) we have to sort the record in certain order. The sort order is very important for displaying records or major calculations. In LINQ for sorting data the order keyword is used.

With the help of the order keyword we can decide on the ordering of the result set that is retrieved after the query.  Below is an simple example of the order keyword in LINQ.

    string[] words = { "cherry", "apple", "blueberry" };

    var sortedWords =

In my last post I talked about how to use the take and the Skip keyword to filter out the number of records that we are fetching. But there is only problem with the take and skip statement. The problem lies in the dependency where by the number of records to be fetched has to be passed to it. Many a times the number of records to be fetched is also based on the query itself.

For example if we want to continue fetching records till a certain condition is met on the record set. Let’s say we want to fetch records from the array of number till we get 7. For this kind of query LINQ has exposed the TakeWhile Method.

    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

In LINQ we can use the take keyword to filter out the number of records that we want to retrieve from the query. Let’s say we want to retrieve only the first 5 records for the list or array then we can use the following query

    int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };

    var first3Numbers = numbers.Take(3);

The TAKE keyword can also be easily applied to list of object in the following way.

LINQ has bought with itself a super power of querying Objects, Database, XML, SharePoint and nearly any other data structure. The power of LINQ lies in the fact that it is managed code that lets you write SQL type code to fetch data. 

Whenever working with data we always need a way to filter out the data based on different condition. In this post we will look at some of the different ways in which we can filter data in LINQ with the help of where clause.

Simple Filter for an array.

Let’s say we have an array of number and we want to filter out data based on some condition. Below is an example