Which LINQ to SQL operation is used to delete records from a database table?

  • DeleteOnSubmit
  • InsertOnSubmit
  • RemoveOnSubmit
  • UpdateOnSubmit
In LINQ to SQL, the operation used to delete records from a database table is DeleteOnSubmit. Similar to insertion and updating, deletion operations are also performed within a DataContext instance. This method queues up objects for deletion, and upon calling SubmitChanges(), the changes are applied to the underlying database. Understanding how to delete records is crucial for maintaining data integrity and managing database content effectively in LINQ to SQL applications.

ADO.NET data providers are responsible for handling ___________ to specific databases.

  • Data queries and manipulation
  • Database connections and communication
  • User authentication and authorization
  • Database backups and recovery
The correct option is Database connections and communication. ADO.NET data providers are responsible for managing the communication between .NET applications and specific databases. This includes establishing connections, executing commands, and retrieving results from the database. They abstract the underlying database details and provide a consistent interface for interacting with different database systems.

The BindingNavigator control in WinForms provides built-in navigation and manipulation options for ___________ controls.

  • ListBox
  • TreeView
  • DataGridView
  • TextBox
The BindingNavigator control in WinForms is primarily used with controls that display tabular data, such as the DataGridView control. It provides built-in navigation and manipulation options like moving to the first or last record, adding new records, or deleting existing records.

When using DataRelations to establish a hierarchy, what is the role of the ParentKeyConstraint and ChildKeyConstraint?

  • Enforces referential integrity between child and parent tables
  • Enforces uniqueness in the parent key column
  • Establishes the relationship between child and parent tables
  • Specifies the data type of the parent key column
The ParentKeyConstraint and ChildKeyConstraint play a crucial role in enforcing referential integrity between child and parent tables in a dataset. The ParentKeyConstraint ensures that each value in the parent key column is unique, while the ChildKeyConstraint enforces that each foreign key value in the child table corresponds to a valid primary key value in the parent table. This helps maintain the integrity of the data hierarchy established through DataRelations.

A parameterized query replaces user input in SQL statements with ________ to prevent SQL injection.

  • functions
  • operators
  • placeholders
  • variables
Parameterized queries replace user input in SQL statements with placeholders. These placeholders act as markers for where the input data should be inserted into the query. By using placeholders, the SQL engine can differentiate between executable SQL code and user-provided data, thereby preventing SQL injection attacks.

What is the purpose of the BeginTransaction method in ADO.NET?

  • To begin a database transaction
  • To establish a connection to the database
  • To execute a SQL command
  • To retrieve data from the database
The BeginTransaction method in ADO.NET is used to initiate a database transaction. It marks the beginning of a sequence of database operations that must be treated as a single unit of work, ensuring data integrity and consistency.

Which method is used to open a database connection in ADO.NET?

  • Begin()
  • Connect()
  • Open()
  • Start()
The method used to open a database connection in ADO.NET is Open(). Calling this method establishes a connection to the database specified by the connection string associated with the connection object.

In Entity Framework, what is the primary purpose of an Entity?

  • Defining the structure of the database
  • Modeling business entities
  • Performing database operations
  • Representing a table in the database
In Entity Framework, an Entity primarily represents a business object or concept, such as a customer or an order. It models the data that the application works with and typically corresponds to a table in the database. Entities in EF are used to perform CRUD (Create, Read, Update, Delete) operations on the underlying data.

LINQ queries can be performed on various data sources, including collections, arrays, and ___________.

  • Databases
  • JSON Files
  • Web Services
  • XML Documents
LINQ allows developers to perform queries not only on collections and arrays but also on XML documents, enabling versatile data manipulation.

Explain the concept of "lazy loading" in Entity Framework and its impact on performance.

  • Automatic loading of related entities without any explicit request, improves performance
  • Deferred loading of related entities until they are specifically requested, can lead to excessive database queries
  • Eager loading of all related entities upfront, reducing database round-trips
  • Manual loading of related entities using custom queries, enhances control over data retrieval
Lazy loading in Entity Framework refers to the practice of deferring the loading of related entities until they are accessed. While this can lead to excessive database queries if not managed properly, it helps improve performance by only loading the necessary data when needed.