Consider a situation where you have to map a complex class hierarchy with minimal database tables. Which inheritance strategy would you choose and what are its implications?
- Joined Tables (JT): Each class in the hierarchy maps to its own database table, with a one-to-one relationship between the base class table and derived class tables.
- Table per Concrete Type (TPC): Each class maps to its own database table, including inherited properties.
- Table per Hierarchy (TPH): All properties from all classes are mapped to a single database table.
- Table per Type (TPT): Each class in the hierarchy maps to its own database table.
Table per Hierarchy (TPH) strategy would be chosen. TPH reduces the number of database tables required by mapping all properties from all classes to a single database table. This strategy simplifies the database schema, making it easier to manage and understand. However, it may result in NULL values for properties specific to certain derived types, impacting database performance and storage efficiency.
When dealing with a legacy database that has a non-standard table structure, how can you implement inheritance in Entity Framework to accommodate this?
- Use Joined Tables (JT) strategy, mapping each class in the hierarchy to its own database table with a one-to-one relationship between the base class table and derived class tables.
- Use Table per Concrete Type (TPstrategy, mapping each class to its own database table, including inherited properties.
- Use Table per Hierarchy (TPH) strategy to map all properties from all classes to a single database table.
- Use Table per Type (TPT) strategy, mapping each class in the hierarchy to its own database table.
Using the Table per Hierarchy (TPH) strategy would be the most appropriate approach. TPH allows mapping all properties from all classes to a single database table, making it suitable for accommodating non-standard table structures in legacy databases. This simplifies the mapping process and aligns well with the existing database schema, reducing the need for extensive schema modifications. However, it's essential to consider potential performance implications, such as NULL values and table size, when implementing this strategy.
How do you call a stored procedure in Entity Framework?
- By adding the stored procedure to the model
- By creating a SqlCommand object
- By executing a LINQ query
- By using the DbContext's Database property
In Entity Framework, stored procedures can be called by using the DbContext's Database property, which provides methods like ExecuteSqlCommand for executing SQL queries or stored procedures directly.
Can functions be executed directly in Entity Framework, and if so, how?
- No, Entity Framework does not support functions
- Yes, by creating a new instance of the function
- Yes, by using the DbContext's ExecuteFunction method
- Yes, by writing raw SQL queries
Functions can be executed directly in Entity Framework by using the DbContext's ExecuteFunction method, which allows invoking database functions mapped in the model.
What is the primary use of stored procedures within Entity Framework?
- Enforcing business logic
- Enhancing performance and security
- Providing a way to write complex queries
- Simplifying database design
The primary use of stored procedures within Entity Framework is to enhance performance and security by reducing the amount of data sent between the database and the application, and by encapsulating business logic on the database server.
How do you map a stored procedure to a domain model in Entity Framework?
- Using the AddFromStoredProcedures method
- Using the Database.ExecuteSqlCommand method
- Using the ImportFunction attribute
- Using the MapToStoredProcedures method
Mapping a stored procedure to a domain model in Entity Framework is typically done using the MapToStoredProcedures method. This method is used to configure Entity Framework to map CRUD operations to specific stored procedures defined in the database, allowing for seamless integration of stored procedures with the domain model. This approach enables developers to leverage the power and efficiency of stored procedures while still working within the Entity Framework framework.
What is required to import a function from a database into your Entity Framework model?
- Adding the function manually in the code
- Using the AddFromFunctions method
- Using the Database.ExecuteSqlCommand method
- Using the ImportFunction attribute
To import a function from a database into your Entity Framework model, you typically use the ImportFunction attribute. This attribute allows you to specify the name of the function in the database that you want to import into your Entity Framework model. By decorating a method in your code with this attribute and providing the name of the function, Entity Framework will automatically map calls to that method to the corresponding database function, providing seamless integration between your code and the database functions.
When would you use a stored procedure over LINQ queries in Entity Framework?
- When dealing with complex business logic or performance optimization
- When the data manipulation requires simple CRUD operations
- When the database schema is subject to frequent changes
- When working with in-memory collections
Stored procedures are typically used over LINQ queries in Entity Framework when dealing with complex business logic or when performance optimization is crucial. While LINQ queries are powerful for querying data in a more expressive and object-oriented manner, stored procedures offer performance benefits and can encapsulate complex logic directly in the database, making them more suitable for scenarios where performance or complex logic are primary concerns.
How does Entity Framework handle output parameters from stored procedures?
- It converts output parameters to return values
- It ignores output parameters
- It maps output parameters to properties of an object
- It throws an error
Entity Framework allows output parameters from stored procedures to be mapped to properties of objects retrieved from the database. This enables developers to easily access data returned by stored procedures.
What are the limitations of using stored procedures with Entity Framework?
- Difficulty in handling complex result sets
- Inability to use stored procedures for data manipulation operations
- Limited support for advanced database features
- Restrictions on executing stored procedures with dynamic SQL statements
Entity Framework has limitations when using stored procedures, such as limited support for advanced database features and restrictions on executing stored procedures with dynamic SQL statements.