What is an anonymous type in LINQ, and how is it used?
- It is a predefined type in LINQ used for query expressions.
- It is a type created dynamically at runtime to encapsulate data.
- It is a type that can only be used within LINQ queries.
- It is a type with no name used for declaring variables.
An anonymous type in LINQ is a type created dynamically at runtime to encapsulate data. It allows you to define a new type without explicitly declaring a class or struct. Anonymous types are typically used to store the results of query expressions or to project data into a new shape. They are convenient for one-time use cases where defining a formal type would be unnecessary overhead. However, they cannot be used outside of the method or scope where they are defined.
When updating data with Entity Framework, you should call the ___________ method to persist the changes to the database.
- ApplyChanges()
- Commit()
- SaveChanges()
- Update()
To persist changes made to data in Entity Framework, you should call the SaveChanges() method. This method commits the changes to the underlying database, ensuring data consistency.
Setting the Nested property of a DataRelation to ___________ enables multi-level hierarchies.
- 0
- 1
- FALSE
- TRUE
When you set the Nested property of a DataRelation to True, it enables the creation of multi-level hierarchies in your DataSet. This means you can navigate through multiple levels of related data using this DataRelation.
The ParentKeyConstraint ensures that parent keys are ___________ and unique.
- Consistent
- Maintained
- Referenced
- Valid
The ParentKeyConstraint in ADO.NET ensures that the parent keys in a relational database are valid, meaning they exist in the parent table, and unique, ensuring data integrity and referential integrity.
Scenario: In a Windows Forms application, you have a requirement to allow users to select multiple items from a ListBox control. How would you implement this feature?
- Set the SelectionMode property of the ListBox control to MultiExtended or MultiSimple.
- Use a CheckedListBox control instead of a ListBox control.
- Handle the ListBox's ItemCheck event and maintain a collection of selected items manually.
- Enable the MultiSelect property of the ListBox control.
Option 1 is the correct approach. Setting the SelectionMode property of the ListBox control to either MultiExtended or MultiSimple allows users to select multiple items by holding down the Ctrl key or dragging the mouse, respectively. This feature provides a straightforward way to implement multiple item selection in a Windows Forms application using standard ListBox controls.
ADO.NET data providers offer optimized data access for ___________ databases.
- MongoDB
- NoSQL
- Relational
- SQL
ADO.NET provides optimized data access for relational databases such as Microsoft SQL Server, Oracle, MySQL, etc. These databases are structured and follow the relational model.
The Update method of a DataAdapter is used to apply changes from a DataSet back to the ___________.
- DataCommand
- DataReader
- DataTable
- Database
The Update method of a DataAdapter is utilized to apply changes made in the DataSet back to the database. It updates the database with changes made in the local DataSet, ensuring data synchronization between the DataSet and the database.
ADO.NET provides a way to interact with databases using ________.
- Classes and Methods
- Data Access Objects
- Data Providers
- Object-Relational Mapping
ADO.NET relies on Data Providers to interact with databases. Data Providers include classes and methods for connecting to, querying, and manipulating data in various database management systems (DBMS).
Scenario: You are tasked with optimizing the performance of an Entity Framework application. What strategies and techniques can you employ to improve database performance?
- Compiled Queries
- Eager Loading
- Lazy Loading
- Query Optimization
Query Optimization involves techniques such as indexing, avoiding unnecessary joins, and using appropriate filtering and sorting to improve database performance. By carefully crafting queries and utilizing database profiling tools, you can identify and address performance bottlenecks. Eager Loading and Lazy Loading are related to how Entity Framework retrieves related data but may not directly address database performance. Compiled Queries can improve performance by caching query execution plans, but they're only one aspect of optimizing database performance.
In ADO.NET, what is the role of parameters in non-query commands?
- Define command type
- Execute the command
- Handle errors
- Provide values
Parameters in non-query commands of ADO.NET are used to provide values dynamically to the command, helping in executing parameterized queries to interact with the database securely and efficiently.