LINQ (Language Integrated Query) is one of the most powerful features in .NET, providing a unified syntax to query collections, databases, XML, and other data sources. Below are 20+ important LINQ concepts, their explanations, and code snippets to help you understand their usage.
1. Where (Filtering)
The Where()
method is used to filter a collection based on a given condition.
2. Select (Projection)
The Select()
method projects each element of a sequence into a new form, allowing transformation of data.
3. OrderBy (Sorting in Ascending Order)
The OrderBy()
method sorts the elements of a sequence in ascending order.
4. OrderByDescending (Sorting in Descending Order)
OrderByDescending()
sorts the elements of a sequence in descending order.
5. First (Get First Element)
First()
returns the first element of a collection that satisfies a condition or throws an exception if none are found.
6. FirstOrDefault (First or Default Value)
FirstOrDefault()
returns the first element or a default value (null or default of type) if none match the condition.
7. Single (Return Exactly One Element)
Single()
returns the only element that satisfies a condition and throws an exception if more than one or no elements are found.
8. SingleOrDefault (Single or Default Value)
SingleOrDefault()
returns the only element that satisfies a condition, or a default value if no elements match.
9. Take (Take First N Elements)
Take()
returns the first n
elements from a collection.
10. Skip (Skip First N Elements)
Skip()
skips the first n
elements and returns the remaining elements.
11. Distinct (Remove Duplicates)
Distinct()
removes duplicate elements from a collection.
12. GroupBy (Grouping Data)
GroupBy()
groups elements of a collection by a specified key.
13. Join (Inner Join)
Join()
is used to combine two collections based on a common key, similar to an SQL inner join.
14. GroupJoin (Left Outer Join)
GroupJoin()
performs a left outer join between two collections, combining each element from the first collection with a group of matching elements from the second collection.
15. Any (Check if Any Element Matches Condition)
Any()
returns true
if any elements in a collection satisfy a condition.
16. All (Check if All Elements Match Condition)
All()
returns true
if all elements in a collection satisfy a condition.
17. Count (Count Elements in a Collection)
Count()
returns the total number of elements or the number of elements matching a condition.
18. Max (Maximum Value)
Max()
returns the maximum value from a collection.
19. Min (Minimum Value)
Min()
returns the minimum value from a collection.
20. Sum (Sum of Values)
Sum()
computes the sum of values in a collection.
21. Average (Average Value)
Average()
computes the average value of a sequence.
22. Zip (Combining Two Sequences)
Zip()
applies a specified function to the corresponding elements of two sequences.
23. SelectMany (Flattening Collections)
SelectMany()
flattens a collection of collections into a single collection.
24. Aggregate (Custom Accumulation Operation)
Aggregate()
applies an accumulator function over a sequence.
25. Union (Combine and Remove Duplicates)
Union()
combines two collections and removes duplicates.
26. Intersect (Common Elements)
Intersect()
returns elements that are present in both collections.
27. Except (Difference between Two Collections)
Except()
returns elements from the first collection that are not in the second collection.
Conclusion
LINQ is an essential feature in .NET that greatly simplifies data querying across various data sources. It promotes cleaner, more readable code, and helps with both in-memory and database
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