Your application involves updating records across different databases. How would you implement distributed transaction management in ADO.NET?
- Data Reader
- OleDbConnection
- SqlCommand
- TransactionScope
Distributed transaction management in ADO.NET can be implemented using TransactionScope. TransactionScope provides a simple and efficient way to manage distributed transactions across multiple databases or resource managers. It automatically handles enlisting connections in the transaction and ensures that either all operations across different databases succeed or fail together, maintaining data integrity and consistency.
Scenario: You are developing a WinForms application that needs to display a list of products from a database. Which control and data binding method would you use to achieve this?
- DataGridView with DataSource property
- ListBox with DataBinding event
- ComboBox with DisplayMember property
- DataGrid with Bind method
The correct option is DataGridView with DataSource property. DataGridView is a versatile control for displaying tabular data and supports data binding through its DataSource property, which allows you to easily bind it to a data source such as a DataTable or a list of objects. This control provides rich functionality for displaying and editing data in a grid format, making it suitable for displaying a list of products from a database.
Which event is triggered when a user selects a row in a DataGrid or DataGridView control?
- CellValueChanged
- RowEnter
- RowHeaderMouseClick
- RowSelected
The "RowEnter" event is triggered when a user selects a row in a DataGrid or DataGridView control. This event occurs when the focus moves to a new row, indicating that the user has selected that row. It provides an opportunity to perform actions based on the selected row, such as retrieving data or updating other controls.
What happens to the data reader when you close the associated database connection?
- The data reader becomes null
- The data reader is disposed automatically
- The data reader remains open
- The data reader throws an exception
When you close the associated database connection, the data reader throws an exception. This is because the data reader relies on the connection to fetch data from the database. Closing the connection while the data reader is still in use results in an exception being thrown to indicate the invalid operation. It's essential to close the data reader before closing the connection to avoid this issue.
What are the advantages of using connection pooling in ADO.NET?
- Enhanced security, Improved performance, Simplified debugging, Increased reliability
- Enhanced security, Simplified debugging, Easier maintenance, Faster deployment
- Improved performance, Reduced overhead, Better scalability, Increased reliability
- Reduced overhead, Better scalability, Easier maintenance, Faster deployment
Connection pooling in ADO.NET improves performance by reusing connections, reducing overhead by eliminating the need to create a new connection for every request, enhancing scalability by efficiently managing connections, and increasing reliability by avoiding connection leaks.
When should you use parameterized queries instead of plain SQL statements?
- When dealing with static data retrieval
- When executing complex joins
- When handling database schema modifications
- When performing queries involving user input
Parameterized queries should be used when performing queries involving user input to prevent SQL injection attacks. By using parameterized queries, input values are treated as data rather than executable code, making it much harder for attackers to inject malicious SQL code into the query. This helps enhance security and protect the database from unauthorized access.
The _________ property of a SqlParameter determines whether a parameter is an input or output parameter.
- Direction
- Name
- Type
- Value
In ADO.NET, the Direction property of a SqlParameter object determines whether the parameter is an input parameter, an output parameter, or both. This property is crucial for specifying the role of the parameter in the stored procedure.
When using a JOIN clause in a SELECT statement, you are typically combining data from ___________ tables.
- Related
- Associated
- Connected
- Linked
The correct option is Option 4: Linked. In SQL, a JOIN clause is used to combine rows from two or more tables based on a related column between them. It links the tables together to create a single, unified dataset for analysis or manipulation.
How can you handle data conflicts when multiple users are trying to modify the same data in a dataset simultaneously?
- Ignore conflicts
- Lock the dataset
- Use optimistic concurrency control
- Use pessimistic concurrency control
Handling data conflicts in ADO.NET involves implementing optimistic concurrency control, where the system assumes that conflicts are rare. When multiple users attempt to modify the same data concurrently, the system checks if the data has been altered since it was retrieved. If the data has changed, it prevents the modification and notifies the user, allowing them to resolve the conflict.
Scenario: You have a DataTable containing sales data for a year. You need to create a DataView that displays only the sales records for a specific region. Which property of the DataView would you use to achieve this?
- AllowNew
- RowFilter
- RowStateFilter
- Sort
The correct option is "RowFilter". This property allows you to specify a filter expression to restrict which rows are viewed in the DataView. By setting the RowFilter property to a condition that filters records based on the specific region, you can achieve the desired outcome.