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.
The ExecuteScalar method is suitable for retrieving a ___________ value from a SELECT statement.
- Single
- Multiple
- Aggregate
- Composite
The correct option is Option 1: Single. The ExecuteScalar method in ADO.NET is used to execute a SQL query that returns a single value, such as a count, sum, average, or any other aggregate or scalar value, typically from a SELECT statement with a WHERE clause.
Which LINQ operator is used to filter elements in a sequence based on a specified condition?
- Filter
- OrderBy
- Select
- Where
The Where operator is used to filter elements in a sequence based on a specified condition. It allows you to specify a predicate function that determines which elements to include in the result sequence.
When using data binding in ADO.NET, what is the role of the DataSource property?
- Binds the data to the UI control
- Executes SQL commands
- Specifies the connection string to the database
- Specifies the name of the database table
The DataSource property in ADO.NET is used to bind data from a data source, such as a dataset or data table, to a UI control, such as a DataGridView or ListBox. It establishes the connection between the data source and the control, enabling the display and manipulation of data in the user interface.
What does LINQ stand for in the context of LINQ to DataSet?
- Language-Integrated Query
- Lightweight Interface for .NET Queries
- Logical Interface for Network Queries
- Longitudinal Inquisitive Query
In LINQ to DataSet, LINQ stands for Language-Integrated Query, which allows developers to query datasets using a syntax similar to SQL within the .NET programming languages such as C# and VB.NET. This provides a more intuitive and readable way to interact with data stored in memory or databases.
The orderby clause is used to ___________ the result set in LINQ to DataSet.
- Filter
- Sort
- Join
- Group
The correct option is 'Sort'. In LINQ to DataSet, the orderby clause is used to sort the result set based on one or more criteria. It allows you to specify the order in which the elements should appear in the result set, such as ascending or descending order.
In Entity Framework, what is the Entity Data Model (EDM)?
- A conceptual model that describes the structure of data, independent of the underlying database schema.
- A mapping mechanism that connects the database schema to the application's object model.
- A set of database tables that represent the entities in an application.
- A tool for querying databases using LINQ expressions.
The Entity Data Model (EDM) in Entity Framework is a conceptual model that represents the structure of data in an application independently of the database schema. It provides a higher-level abstraction over the database, allowing developers to work with entities and relationships in a more intuitive manner.
In LINQ, what is the primary purpose of the join clause?
- Combine two or more sequences based on a related key
- Filter elements based on a specified condition
- Group elements based on a specified key
- Sort elements in ascending or descending order based on a specified key
The primary purpose of the join clause in LINQ is to combine two or more sequences based on a related key. It allows for creating a combined result set from two or more collections based on a common field or property. This operation is akin to SQL JOIN operation.
Scenario: Your project involves interacting with a SQL Server database. Which LINQ technology is the most appropriate choice for querying and manipulating data in the database?
- LINQ to Entities
- LINQ to Objects
- LINQ to SQL
- LINQ to XML
LINQ to SQL is specifically designed for querying and manipulating data in SQL Server databases. It allows developers to write LINQ queries directly against the database entities, providing a strongly-typed approach to database access and manipulation.
Which ADO.NET class represents a command object for executing SQL queries and stored procedures in SQL Server?
- SqlCommand
- SqlConnection
- SqlDataAdapter
- SqlDataReader
The SqlCommand class in ADO.NET represents a command object specifically designed for executing SQL queries and stored procedures in SQL Server. It provides methods for executing commands and retrieving results from the database.