Table Per Type (TPT) mapping strategy in Entity Framework is used for complex inheritance scenarios where each derived type is mapped to its own table, containing only the properties specific to that type. This approach ensures a normalized database schema and allows for efficient querying and data retrieval without redundancy. TPH maps all types in an inheritance hierarchy to a single table, leading to potential data integrity and performance issues. TPC maps each concrete class to its own table, resulting in redundant columns and denormalized data. TPE is not a standard mapping strategy in Entity Framework.

In a Code-First approach with Entity Framework, database schema changes are managed through migrations. When developers modify the application's data model, Entity Framework generates migration files that represent these changes. Developers can then apply these migrations to update the database schema incrementally. Entity Framework tracks the history of migrations applied to the database, allowing developers to roll back changes if needed. This approach enables developers to evolve the database schema alongside the application's data model while preserving existing data.

Data readers in ADO.NET are primarily used for reading data from the database. They provide a lightweight and efficient way to sequentially retrieve query results, allowing applications to process large datasets without the overhead of loading the entire result set into memory. While data readers excel at data retrieval operations, they are not designed for updating or modifying data in the database, as they provide read-only access to query results.

The where clause in LINQ is primarily used for filtering elements based on specified criteria, allowing developers to select only those that meet certain conditions.

SqlCommand.ExecuteScalar method is the correct option. It executes the query and returns the first column of the first row in the result set returned by the query. This method is typically used for executing commands such as SELECT statements that return a single value.

The correct option is Where and Select. You would use the Where operator to filter the products that are in stock and have a price greater than $50, and then use the Select operator to project the results into a new collection containing only the required product information. This combination allows you to filter and select the desired products in a single query.

In SQL, the SELECT statement retrieves data from one or more tables in a database. It allows you to specify which columns to retrieve and may include conditions to filter rows. The fundamental purpose of the SELECT statement is to fetch data from the database tables.

Recursive queries in LINQ can cause performance degradation, especially with large datasets, due to the iterative nature of their execution. It's recommended to avoid them for better performance.

DbSet in Entity Framework represents a collection of entities of a specified type in the context. It allows developers to perform CRUD operations (Create, Read, Update, Delete) on entities of that type within the context, providing a high-level abstraction over database tables.

To create a filtered view of data from a DataSet using DataViews, you can use the RowFilter property of the DataView. This property allows you to specify filter criteria based on column values, thereby creating a filtered view of the data according to your requirements.