In ADO.NET, what is an optimistic concurrency model?
- Lock-based concurrency model
- Pessimistic concurrency model
- Row versioning concurrency model
- Timestamp-based concurrency model
In an optimistic concurrency model, multiple users are allowed to access and modify data simultaneously without locking the data. Instead, when updating data, ADO.NET compares the original data with the current data to ensure that no changes have occurred since the data was initially retrieved.
You want to call a stored procedure in ADO.NET that updates multiple records in a database. What is the recommended approach for handling the output and any potential errors?
- Use SqlCommand.ExecuteNonQuery method to execute the stored procedure. Check for any errors using try-catch block and handle the output as needed.
- Use SqlCommand.ExecuteReader method to execute the stored procedure and handle any output or errors using SqlDataReader.
- Use SqlConnection to execute the stored procedure and handle output using SqlDataReader.
- Use SqlDataAdapter to execute the stored procedure and handle output using DataSet.
SqlCommand.ExecuteNonQuery method is the recommended approach. It executes the SQL statement against the connection and returns the number of rows affected. Errors can be caught using a try-catch block. SqlDataReader is used for reading a forward-only stream of rows.
In LINQ to SQL, DataContext manages the ___________ between your application and the database.
- Communication
- Connection
- Interaction
- Transaction
DataContext manages the connection between your application and the database in LINQ to SQL. It tracks changes made to the objects and submits them to the database. This ensures efficient communication and interaction with the database.
In LINQ to SQL, the DataContext class represents the ___________.
- Connection to the Database
- Object Model
- Query
- Table in the Database
The DataContext class in LINQ to SQL represents the connection to the database. It manages database connections and transactions and provides methods for querying and submitting changes to the database.
The DataAdapter's Update method is used to ___________ changes made to a dataset back to the database.
- Reflect
- Submit
- Propagate
- Transfer
The correct option is "Propagate". The Update method of DataAdapter propagates changes from the DataSet to the corresponding data source in the database.
In LINQ to Entities, what is the primary purpose of the DbContext class?
- Handles database connection and authentication
- Provides metadata about the database schema
- Represents a collection of database entities
- Represents a session with the database and provides CRUD operations on entities
In LINQ to Entities, the DbContext class serves as a bridge between the domain classes (entities) in the application and the database. It represents a session with the database and provides CRUD (Create, Read, Update, Delete) operations on entities, allowing developers to interact with the database using object-oriented principles.
A dataset in ADO.NET can be thought of as an in-memory ___________.
- Database
- Dataset
- Recordset
- Table
In ADO.NET, a dataset represents an in-memory cache of data retrieved from a data source, which can hold multiple tables, relationships, and constraints.
Scenario: You want to update an existing order's shipping address in a SQL Server database using LINQ to SQL. Which LINQ to SQL method or operation is appropriate for this situation?
- Attach
- InsertOnSubmit
- SubmitChanges
- Update
SubmitChanges method is appropriate for updating existing records in a LINQ to SQL data context. After making changes to the object properties, calling SubmitChanges persists those changes to the database. Attach is used to attach existing objects to a data context, not for updates. Update is not a direct method in LINQ to SQL for updating records. InsertOnSubmit is used for inserting new records, not for updating existing ones.
In data binding, what is the role of the data source?
- Displaying data in a user-friendly format
- Executing SQL commands
- Formatting data for display
- Providing access to data
The data source in data binding acts as the provider of data to be bound to controls. It could be a database, XML file, or any other source containing the required data. The data source serves as the bridge between the application and the underlying data, facilitating seamless interaction between them.
What role does the AcceptChanges method play in data concurrency management in ADO.NET?
- It applies any pending changes to the DataRow and resets its state to unchanged.
- It discards any pending changes made to the DataRow and keeps its state as unchanged.
- It marks the DataRow for deletion and removes it from the DataTable.
- It rolls back any pending changes made to the DataRow and keeps its state as modified.
In ADO.NET, the AcceptChanges method is used in data concurrency management to apply any pending changes to the DataRow and reset its state to unchanged. This method is typically called after updating a DataRow to commit the changes to the underlying database and ensure data integrity.