When working with LINQ to Entities, the "Include" method is used to specify ___________ properties to be eagerly loaded.
- Associated
- Joined
- Navigation
- Related
In LINQ to Entities, the "Include" method is used to specify navigation properties to be eagerly loaded. Navigation properties are properties on an entity that allow you to navigate to related entities.
LINQ allows developers to query and manipulate which types of data sources?
- Arrays
- Collections
- Databases
- XML
LINQ (Language Integrated Query) enables developers to query and manipulate collections, databases, XML documents, and any data source that can be queried with LINQ. It's a versatile tool for working with different types of data sources, making it easier to write expressive and powerful queries in C# and other .NET languages.
What does LINQ to SQL provide when working with relational databases?
- Asynchronous Queries
- Data Encryption
- Direct Access to SQL Server
- Object-Relational Mapping
LINQ to SQL provides object-relational mapping (ORM), allowing developers to work with relational databases using familiar object-oriented programming concepts. It facilitates the translation of relational data into objects, simplifying database operations in .NET applications.
What are the potential consequences of a successful SQL injection attack on a database?
- Corruption of database records
- Denial of service
- Execution of arbitrary SQL commands
- Unauthorized access to sensitive data
A successful SQL injection attack can have severe consequences for a database. Attackers can gain unauthorized access to sensitive data, such as user credentials, personal information, or financial records. They can also modify or delete existing data, leading to data corruption. Additionally, attackers can execute arbitrary SQL commands, giving them full control over the database and potentially compromising its integrity and confidentiality. In some cases, SQL injection attacks can also lead to denial of service by overwhelming the database server with malicious queries, causing it to become unresponsive.
Scenario: What is the significance of the AcceptChangesDuringUpdate property when dealing with data conflicts in ADO.NET?
- It controls the behavior of the data adapter during batch update operations.
- It determines whether changes made to a DataRow during an update operation are accepted or rejected.
- It sets the timeout period for database connections.
- It specifies the isolation level for database transactions.
The AcceptChangesDuringUpdate property in ADO.NET determines whether changes made to a DataRow during an update operation are accepted or rejected. When set to true, changes made to the DataRow are accepted and the DataRow's state is changed to Unchanged after the update operation completes successfully. If set to false, the DataRow retains its modified state, allowing you to review and handle conflicts manually.
In LINQ, what is deferred execution, and why is it important?
- It executes queries asynchronously to prevent blocking.
- It executes queries in parallel to improve performance.
- It is the immediate execution of queries to retrieve data.
- It postpones the execution of queries until the results are needed.
Deferred execution in LINQ means that the query is not executed immediately when it is defined, but rather when the results are actually accessed. This is important because it allows for more efficient use of resources by delaying the execution until necessary, which can lead to better performance and reduced memory consumption, especially when dealing with large datasets or complex queries.
When optimizing LINQ queries, using the ___________ method can help in reducing the number of database round trips.
- FirstOrDefault()
- Include()
- Skip()
- ToList()
The correct answer is ToList(). When you use ToList() method, it retrieves all the data from the database at once and then performs operations on it in memory. This can reduce the number of database round trips by fetching all data needed in a single trip, potentially improving performance.
In LINQ, what is the purpose of the select clause?
- To filter the results
- To join the results
- To project the results
- To sort the results
The purpose of the select clause in LINQ is to project the results. It allows you to define the shape of the result set by selecting specific fields or transforming the elements of the source sequence into a new form.
What is the difference between optimistic concurrency and pessimistic concurrency in ADO.NET?
- Optimistic concurrency assumes that conflicts between multiple users updating the same data are unlikely, so it allows multiple users to access and modify data concurrently without locking it.
- Optimistic concurrency locks the data when it's being accessed by one user to prevent other users from modifying it simultaneously.
- Pessimistic concurrency allows multiple users to access and modify data concurrently without locking it.
- Pessimistic concurrency assumes that conflicts between multiple users updating the same data are likely, so it locks the data when it's being accessed by one user to prevent other users from modifying it simultaneously.
Optimistic concurrency and pessimistic concurrency are two approaches to handling concurrent data access in ADO.NET. Optimistic concurrency assumes that conflicts between multiple users updating the same data are unlikely, so it allows multiple users to access and modify data concurrently without locking it. Pessimistic concurrency, on the other hand, assumes that conflicts are likely, so it locks the data when it's being accessed by one user to prevent other users from modifying it simultaneously.
To improve query performance in Entity Framework, you can use ___________ loading to retrieve related entities in a single query.
- Deferred
- Dynamic
- Eager
- Lazy
Eager loading allows Entity Framework to load related entities along with the main entity in a single query, thus reducing the number of database round-trips and improving performance. It eagerly loads the related entities as part of the initial query execution. It's suitable for scenarios where you know in advance that you will need the related entities.