LINQ to Entities queries are converted to ________ at runtime.
- HTML queries
- JSON queries
- SQL queries
- XML queries
The correct answer is SQL queries. LINQ to Entities translates LINQ queries into SQL queries at runtime, enabling interaction with the underlying database through LINQ syntax, which provides a more natural and expressive way to query data.
The ________ extension method can be used to include related entities in a query result.
- Concat()
- Include()
- Join()
- SelectMany()
The correct answer is Include(). The Include() extension method is used to specify related entities to be included in the query result. It is commonly used to eagerly load navigation properties and retrieve related data along with the main entity.
To improve performance, LINQ to Entities utilizes ________ to avoid retrieving all columns of a table.
- Deferred Execution
- Eager Loading
- Lazy Loading
- Projection
Projection - LINQ to Entities allows for projecting only the necessary columns from a table, which can significantly enhance performance by avoiding the retrieval of unnecessary data. Lazy Loading, Eager Loading, and Deferred Execution are related concepts but do not directly address the optimization of column retrieval in LINQ to Entities.
When dealing with enum types, LINQ to Entities requires explicit ________ to match the database's data type.
- Enum Declaration
- Enum Mapping
- Type Casting
- Type Conversion
Enum Mapping - When using enum types in LINQ to Entities, explicit enum mapping is necessary to ensure that the enum types in the .NET code are properly matched with the corresponding database data types. Type Casting and Type Conversion are broader concepts that may apply in different contexts but are not specifically tied to enum handling in LINQ to Entities. Enum Declaration refers to the creation of enums and is not directly relevant to matching database data types.
The use of ________ in LINQ to Entities can optimize queries by filtering data at the database level.
- Compiled Queries
- Indexes
- Stored Procedures
- Where Clauses
Where Clauses - LINQ to Entities allows developers to use familiar C# syntax to construct queries, including the use of Where clauses, which are translated into SQL WHERE clauses. Utilizing Where clauses can optimize queries by filtering data at the database level, reducing the amount of data transferred between the database and the application. Stored Procedures, Indexes, and Compiled Queries are all techniques used for optimization but do not directly relate to filtering data at the database level through LINQ to Entities.
In a scenario where you need to filter and sort large datasets, how would you efficiently use LINQ to Entities?
- Use IQueryable for deferred execution
- Use compiled queries to optimize performance
- Use eager loading to fetch all data upfront
- Use lazy loading to load related entities on demand
LINQ to Entities provides IQueryable interface for deferred execution. It enables building dynamic queries and executing them efficiently. By using IQueryable, you can apply filters and sorting criteria to the query without actually executing it until necessary, hence optimizing performance for large datasets.
Consider a complex query involving multiple entities and aggregate functions. How would LINQ to Entities be utilized?
- Use LINQ's deferred execution to postpone query execution
- Use LINQ's lazy loading feature to fetch related entities
- Utilize LINQ's ability to perform data validations
- Utilize LINQ's ability to perform joins and aggregate functions
LINQ to Entities allows writing complex queries involving multiple entities and aggregate functions by leveraging its support for joins, groupings, and aggregate functions. By using LINQ's expressive syntax, developers can construct complex queries in a readable and maintainable manner, making it ideal for handling intricate scenarios.
How does indexing affect query performance in Entity Framework?
- Degrades query performance
- Depends on the scenario
- Improves query performance
- No impact
Indexing typically improves query performance by enabling the database engine to locate rows more efficiently. It helps in reducing the number of rows that need to be scanned, resulting in faster query execution.
Describe a scenario where you would use LINQ to Entities to handle data relationships and hierarchies.
- Fetching a user's orders along with details such as order items and shipping address
- Filtering data based on user-defined criteria
- Retrieving hierarchical data like category trees from a database
- Validating data integrity constraints using LINQ
LINQ to Entities is commonly used to handle data relationships and hierarchies, such as fetching related entities like orders, order items, and shipping addresses. It simplifies querying hierarchical data structures like category trees by leveraging its support for navigating relationships defined in the entity model.
What is the impact of Lazy Loading on the performance of an Entity Framework application?
- Decreases performance
- Depends on the scenario
- Increases performance
- No impact
Lazy loading can decrease performance as it may lead to the N+1 query problem, where multiple round trips to the database are made. Each navigation property access triggers a separate query, which can significantly affect performance.