In a customer database, how would you use aggregate functions to determine the average age of all customers?
- AVG(age)
- MAX(age)
- MIN(age)
- SUM(age)
To determine the average age of all customers, you would use the AVG() aggregate function. This function calculates the average value of the specified column, providing the mean age of all customers in the database.
For a reporting feature, how would you implement aggregate functions to display both the highest and lowest values in a single query?
- COUNT(value), AVG(value)
- MAX(value), MIN(value)
- MAX(value), SUM(value)
- SUM(value), AVG(value)
To display both the highest and lowest values in a single query, you would use the MAX() and MIN() aggregate functions. These functions retrieve the maximum and minimum values from the specified column, respectively.
What is a non-entity type in the context of Entity Framework?
- Complex Type
- Foreign Key
- Navigation Property
- Primary Key
In Entity Framework, a non-entity type refers to a type that doesn't map to a table in the database, like a Complex Type. Complex Types are used to represent a structure that doesn't have an identity of its own.
How do you typically perform a query on a non-entity type in Entity Framework?
- Use Entity SQL
- Use LINQ queries
- Use SQL queries
- Use Stored Procedures
In Entity Framework, querying non-entity types is typically done using LINQ queries. LINQ provides a powerful and intuitive way to query various data sources, including non-entity types.
What is the primary difference between entity types and non-entity types in Entity Framework?
- Entity types can have relationships with other entities
- Entity types represent tables in the database
- Non-entity types cannot be used in queries
- Non-entity types have no identity
The primary difference lies in identity and persistence. Entity types map to tables in the database and have an identity, while non-entity types like Complex Types have no identity and don't directly map to tables.
When querying a non-entity type, which method is commonly used to define the query result shape?
- Select
- Include
- Where
- Join
The correct option is Option 1: Select. When querying a non-entity type in Entity Framework, the Select method is commonly used to define the shape of the query result. This method allows you to specify which properties or fields you want to include in the result set.
How can you perform a join operation between an entity type and a non-entity type in a LINQ query?
- Join
- Include
- Where
- Select
The correct option is Option 1: Join. To perform a join operation between an entity type and a non-entity type in a LINQ query, you would typically use the Join method. This method allows you to combine records from two different collections based on a specified condition.
Entity Framework allows mapping of stored procedure results to non-entity types using the ________ configuration.
- MapTo
- FromSql
- ToList
- MapToSql
The correct option is "FromSql." In Entity Framework, the FromSql method is used to execute a raw SQL query or call a stored procedure and map the result to non-entity types. It allows you to work with the result set returned by the stored procedure efficiently.
What is required to map a query to a non-entity type in Entity Framework?
- DbQuery
- DbSet
- DbFunction
- DbSqlQuery
The correct option is Option 1: DbQuery. To map a query to a non-entity type in Entity Framework, you need to use the DbQuery class. DbQuery represents a LINQ to Entities query that returns non-entity types, such as primitive types or anonymous types.
In complex queries involving non-entity types, how does Entity Framework handle performance optimization?
- It employs lazy loading strategies
- It leverages caching mechanisms for improved performance
- It utilizes LINQ query optimization techniques
- It utilizes precompiled queries for faster execution
Entity Framework optimizes performance in complex queries involving non-entity types by utilizing LINQ query optimization techniques. These techniques involve query translation, which converts LINQ queries into SQL queries optimized for the underlying database. By doing so, Entity Framework can execute queries more efficiently, resulting in improved performance.