1) Explain
what is LINQ? Why is it required?
Language Integrated
Query or LINQ is the collection of standard query operators which provides
query facilities into.NET framework language like C#, VB.NET.
LINQ is required as it
bridges the gap between the world of data and world of objects.
2) What
are the types of LINQ?
· LINQ to Objects
· LINQ to XML
· LINQ to Dataset
· LINQ to SQL
· LINQ to Entities
3) Explain
how LINQ is useful than Stored Procedures?
Debugging: It is difficult to debug a stored procedure but
as LINQ is part of.NET, visual studios debugger can be used to debug the queries .
Deployment: For stored procedure, additional script should
be provided but with LINQ everything gets compiled into single DLL hence
deployment becomes easy .
Type Safety: LINQ is type safe, so queries errors are type
checked at compile time .
4) List
out the three main components of LINQ? Explain what is the extension of the
file, when LINQ to SQL is used?
Three main components
of LINQ are
· Standard Query
Operators .
· Language
Extensions .
· LINQ Providers .
The extension of the
file used is .dbml .
5) Define
what is Where clause and Let clause?
Where clause: It allows adding some conditional filters to the
query.
Let clause: It allows defining a variable and assigning it a
value calculated from the data values.
6) Explain
why SELECT clause comes after FROM clause in LINQ?
With other programming language
and C#, LINQ is used, it requires all the variables to be declared first.
“FROM” clause of LINQ query defines the range or conditions to select records.
So, FROM clause must appear before SELECT in LINQ.
7) Explain
what is the use of System.XML.Xlinq.dll?
System.Data.Dlinq.dll
provides the functionality to work with LINQ to SQL .
8) Explain
what is lambda expressions in LINQ?
Lambda expression is
referred as a unique function use to form delegates or expression tree types,
where right side is the output and left side is the input to the method. For
writing LINQ queries particularly, Lambda expression is used.
9) Explain
how LINQ with databases can be used?
LINQ supports XML, SQL,
Dataset and Objects. Through LINQ to objects or LINQ to Datasets one can use
LINQ with other databases. The objects and datasets take care of database particular
operations, and LINQ only needs to deal with those objects and not the database
operations directly.
10)
Explain what is the difference between Skip() and SkipWhile() extension method?
Skip() : It will take an integer argument
and from the given IEnumerable it skips the top n numbers .
SkipWhile (): It will continue to skip the elements as far as
the input condition is true. It will return all remaining elements if the
condition is false .
11) In
LINQ how will you find the index of the element using where () with Lambda
Expressions?
In order to find the
index of the element using where () with the lambda expression
Where ( ( i, ix ) =>
i == ix);
12)
Explain how you can assign a lambda expression to a delegate?
To assign a lambda
expression to a delegate
Delegate int del (int
i);
Del
myDelegate=x=>x*x;
Intj = myDelegate (4);
//j=16
13)
Explain what is the difference between Statement Lambda and Expression Lambda?
Expression Lambdas are
extensively used in the construction of Expression Trees .
To create expression
trees statement lambdas cannot be used .
14)
Mention what is the role of DataContext classes in LINQ?
DataContext class acts
as a bridge between SQL Server database and the LINQ to SQL. For
accessing the database and also for changing the data in the database, it
contains connections string and the functions.
15)
Explain what are LINQ query expressions?
Query expression is
nothing but an LINQ query. It is a combination of query clauses that identifies
the data sources for a query. It contains information for sorting, filtering,
grouping or joining to apply to the source data. It determines what information
should be retrieved from the data source.CV.
16)
Explain what are compiled queries?
In compiled LINQ
queries, the plan is cached in a static class and static class is a global
cache. Rather than preparing the query plan from scratch, LINQ prepares plan using
stating class object.
17)
Explain how standard query operators useful in LINQ?
Standard Query
Operators useful in LINQ are
·
Get a total count
of elements in the collection .
·
Order the results
of a collection .
·
Grouping .
·
Computing average .
·
Joining two
collections based on matching keys .
·
Filter the results .
18)
Explain what is the purpose of LINQ providers in LINQ?
LINQ providers are set
of classes that take an LINQ query which generates method that executes an
equivalent query against a particular data source.
19)
Explain how you can retrieve a single row with LINQ?
To retrieve a single
row with LINQ we need
Public User GetUser
(string userName)
{
DBNameDataContext
myDB = new DBNameDataContext ( ) ;
User user = myDB.
Users. Single ( u, u.UserName => userName );
Return user;
}
20) LINQ
query is executed in which statement?
In VB, an LINQ query is
executed in the For Each Statement, and in the foreach statement for C#.
21)
Explain what is “LINQ to Objects”?
When LINQ queries any
IEnumerable(Of T) collection or IEnumerable directly without the use of an
intermediate LINQ provider or API such as LINQ to SQL or LINQ to XML is
referred as “LINQ to Objects.”
22)
Explain how you can differentiate between Conversion Operator “ToDictionary”
and “IEnumerable” of LINQ?
To solve the conversion
type problems “IEnumerable” and “ToDictionary” conversion operator are used.
“ToDictionary”
conversion operator is the instance of Dictionary (k, T). The “keySelector”
predicate recognizes the key of each item, while “elementSelector”, is used to
extract each single item, if it is given.
Extension method on
“IEnumerable” is.AsEnumerable. AsEnumerable simply returns the source sequence
as an object of type IEnumerable <T>.
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