Updated April 4, 2023
Introduction to LINQ
LINQ stands for Language Integrated Query and it is a product of Microsoft .NET Framework modules which connect local data queries to .Net languages. LINQ is an innovative thing that is used connecting between two platforms called Visual Studio and .NET Framework. LINQ is fully integrated and we can easily retrieve data from databases, in-memory objects, and XML documents. LINQ code is a readable one that defines the standard approach to querying the different data sources. Let’s see some of the frequently asked interview questions in LINQ with their answers; it might help for further exams and also for interviews,
LINQ Interview Questions with their Answers
Let us discuss the interview questions of LINQ.
1.Explain LINQ and its essential role?
LINQ (Language Integrated Query) is a set of standard queries which helps to make available query services into the .NET Framework languages like VB.Net, C#. The essential role of LINQ is in integrating the query facility into several .Net Languages it’s like bridging between the data and objects.
2.What are the different types of LINQ?
- LINQ to Objects
- LINQ to DataSet
- LINQ to XML (XLINQ)
- LINQ to SQL (DLINQ)
- LINQ to Entities
3. How many types of Joins in LINQ?
There are four types of Joins in LINQ, they are
- Inner Join
- Left Outer Join
- Cross Join
- Group Join
4.Share the difference between First() and FirstOrDefault()?
First() will throw an exception if there are no records to return whereas FirstOrDefault() returns NULL if no record is found.
5.What are the LINQ Quantifier Operators and Explain?
LINQ Quantifier in nothing but returns the Boolean value as a result, which means it checks whether all or some of the values in the data source satisfy the given condition and returns the result either true or false. There are three operators,
- All() – it checks whether all the elements in the data source satisfies the given condition
- Any() – it checks whether any or at least one of the elements in the data source satisfies the given condition
- Contains() – it checks whether the data source contains that specific element.
Those three methods return only Boolean values as a result; either true or false depends on the elements in the data source and which satisfies the condition.
6. What are the advantages of using LINQ over Stored Procedures?
- LINQ is a type-safety so during compile time itself query errors are checked.
- In LINQ debugging is easy during development, whereas in stored procedures the GUI data will take time so it will be time-consuming.
- In LINQ there is no further task to deploy it, but in a stored procedure, it takes the entire process to deploy it. In LINQ deployment is easy.
7. What are projection operators?
The Projection Operators are of two types, they are
- Select() it selects a value from the collection of items.
- SelectMany() it selects the value from the group of the collection which is called a nested collection.
8.What’s the extension of LINQ to SQL file is used?
The extension used for this file is .dbml.
9.Explain distinct operator in LINQ with example?
LINQ distinct operator comes under Set Operator, where it removes the duplicate values from the collection and returns the unique values. Distinct operator only available in method syntax it does not support query syntax.
For example:
listItems= { 22,33,44,22,22,55,77,55,33,88}
result=listItems.distinct();
Result: {22, 33, 44, 55, 77, 88}
10.What are the LINQ sorting operators and explain it types with syntax?
Sorting operator is used to re-arrange the given sequence of items into ascending or descending order based on the attributes. There are five different sorting operators they are
1. OrderBy – used to sort the elements in either ascending or descending order
a. var data_in_OrderBy = productList.OrderBy(p => p.productName);
2. OrderByDescending – it sorts the elements in descending order only.
a. var data_in_OrderByDesc = productList.OrderByDescending(p => p. productName);
3. ThenBy- it is used only for a secondary purpose, once the orderBy function is done it will proceed.
a. var data_ThenBy = productList.OrderBy(p => p. productName).ThenBy(p => p.productCost);
4. ThenByDescending-it is also used once the orderByDescending is completed, once the primary sorting is done, this sort will proceed.
a. Var data_ThenByDesc = productList.OrderBy(p => p. productName).ThenByDescending(p=> p.productCost);
5. Reverse- reverse sort is nothing but it displays the order in opposite direction, ascending and descending order in not applicable it displays the elements in reverse order from the current position.
a. var data _Reverse= productList.Reverse();
11.What is DataContext class in LINQ?
DataContext class in LINQ acts as a bridge between SQL Server database and LINQ to SQL, for the use of database and further updations in database, it uses the connection string and some functionality to make it. It performs three basic tasks to achieve it. To create connection to database, it retrieves and submits the objects to the database
Converts object to SQL queries and so on.
12. What are Lambda and Query expressions in LINQ?
Lambda Expression uses the lambda operator => it is a function without specifying the name which calculates and returns the result as a single value, here in the operator => in the left side it specifies the input data and in right side having the statement blocks \ expressions. Query Expression it contains the combination of queries that identifies the data sources for query, it has criteria of sorting, grouping, joining, filtering to make use of data source. The LINQ query expressions are similar to SQL syntax, it simply specifies what the data should be retrieved from the data source.
13.What are the Entity Classes in LINQ?
Entity classes are now mainly used in all programming, it is the fundamental building block on developing LINQ, in this class, it is generally an object wrapper of a database table and it has the stereotype of the entity.
Conclusion
In this article, we have providing collection of LINQ Interview questions with their corresponding answers which help to enhance your skill sets and confidence to crack any interviews or for any exams to achieve your desired goal. Hope the article helps you to crack the upcoming exams and interviews in LINQ.
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