How can you implement custom data binding in a WinForms application?
- Implement the IDataBinding interface, override the necessary methods, and manually bind data to controls
- Implement the INotifyPropertyChanged interface in the data source class, handle the PropertyChanged event, and update the bound controls accordingly
- Inherit from the Control class, override the DataBind method, and define custom binding logic
- Use the Binding class to create custom binding expressions, handle the DataBinding event, and manually update the controls
Custom data binding in WinForms can be implemented by making the data source class implement the INotifyPropertyChanged interface. This allows the data source to notify the UI controls when a property value changes, ensuring that the bound controls reflect the updated data.
Data binding to list controls simplifies the process of presenting ___________ from a data source to users.
- Hierarchical data
- Tabular data
- Structured data
- Unstructured data
The correct option is 2. Tabular data. Data binding to list controls simplifies the process of presenting tabular data from a data source to users, making it easier to display information in a structured and organized format.
In Entity Framework, what does the Code-First approach emphasize?
- Code-based entity and database creation
- Database-first design
- Model-first development
- Database schema generation
The correct option is Code-based entity and database creation. The Code-First approach in Entity Framework emphasizes defining your domain model using plain CLR objects (POCO classes) and then creating the database from these classes.
Scenario: Your application needs to retrieve data from a database and display it in a tabular format. Which ADO.NET control or component would be suitable for this purpose?
- DataGrid
- DataGridView
- ListBox
- TextBox
DataGridView is a versatile ADO.NET control used to display data in a tabular format. It provides features like sorting, filtering, and editing of data, making it suitable for displaying database query results in a tabular format within applications.
When using a data reader, what is the typical sequence of operations for reading data?
- Execute the query, Open the connection, Close the connection, Read the data
- Execute the query, Read the data, Close the connection, Open the connection
- Open the connection, Close the connection, Execute the query, Read the data
- Open the connection, Execute the query, Read the data, Close the connection
When using a data reader, the typical sequence of operations involves opening the connection to the database, executing the query to retrieve data, reading the data sequentially, and then closing the connection. This sequence ensures efficient data retrieval and resource management.
Scenario: A user wants to delete a record from a dataset, but you want to ensure that the deletion is not permanent until the user confirms. What ADO.NET functionality can help you achieve this?
- Implementing a custom rollback mechanism
- Using DataAdapter's DeleteCommand property
- Using DataAdapter's Fill and Update methods
- Using DataTable's RejectChanges method
DataTable's RejectChanges method allows reverting changes made to a DataTable since it was loaded or since the last AcceptChanges call. By calling this method, you can undo deletion of records until changes are permanently saved to the database. This provides a safety net for users before committing irreversible changes.
You need to retrieve a list of customers from a database using LINQ to Entities. What LINQ operator would you use to filter customers whose last names start with "Smith"?
- Where
- StartsWith
- Contains
- Like
The correct option is "StartsWith." This operator is used in LINQ to Entities to filter records based on the beginning characters of a string. It's suitable for filtering last names that start with "Smith."
How can you define complex queries involving multiple tables in LINQ to Entities?
- By using navigation properties to traverse relationships between entities
- By using the "GroupBy" clause to group related entities
- By using the "OrderBy" clause to sort entities based on a specified key
- By using the "Select" clause to project specific properties from related entities
Complex queries involving multiple tables in LINQ to Entities can be defined by using navigation properties to traverse relationships between entities. Navigation properties allow you to navigate from one entity to related entities, enabling the construction of queries that involve multiple tables and their relationships.
How can you specify a connection string in a .NET application configuration file?
- By adding a
section and defining a element within it - By embedding the connection string directly into the code
- By using a predefined system variable
- By using a separate text file for storing connection strings
In .NET applications, connection strings are typically stored in the application configuration file (app.config or web.config). This can be done by adding a section within the configuration file and defining one or more elements, each containing the connection string details. This approach allows for easy maintenance and modification of connection strings without modifying the code.
In ADO.NET, what is the difference between a local transaction and a distributed transaction?
- A local transaction can only be used with SQL Server, while a distributed transaction works with any database.
- A local transaction involves a single database, while a distributed transaction spans multiple databases or systems.
- A local transaction is faster than a distributed transaction.
- A local transaction is managed entirely by the application, while a distributed transaction requires coordination by a distributed transaction coordinator.
The key difference between a local transaction and a distributed transaction in ADO.NET lies in their scope. A local transaction involves operations within a single database, whereas a distributed transaction extends across multiple databases or systems. A distributed transaction also requires coordination by a distributed transaction coordinator, which adds complexity compared to local transactions.