What is the difference between EntityState.Added and EntityState.Modified in Entity Framework?
- EntityState.Added implies the entity is in a detached state, while EntityState.Modified implies it's in an attached state
- EntityState.Added indicates that the entity is being inserted into the database, while EntityState.Modified indicates that the entity has been changed and needs to be updated in the database
- EntityState.Added means the entity is in a transient state, while EntityState.Modified means the entity is being tracked for changes
- EntityState.Added represents a new entity that has been added to the context and is not yet saved in the database, whereas EntityState.Modified indicates that the entity exists in the database and has been modified
EntityState.Added signifies that the entity is newly created and has not been saved to the database yet. EntityState.Modified indicates that the entity already exists in the database but has been modified and needs to be updated when changes are saved.
In ADO.NET, what is the purpose of the AcceptChanges and RejectChanges methods in the DataRow?
- AcceptChanges commits changes to the DataRow
- AcceptChanges discards changes made to the DataRow
- RejectChanges commits changes to the DataRow
- RejectChanges discards changes made to the DataRow
The AcceptChanges method in DataRow commits changes made to the DataRow, effectively updating the DataRow's state to reflect the modifications. On the other hand, the RejectChanges method discards any changes made to the DataRow since it was last updated, reverting it to its original state. These methods are crucial for managing the state of DataRow objects within a DataTable.
Which LINQ operator is used to filter elements in a collection based on a specified condition?
- GroupBy
- OrderBy
- Select
- Where
The "Where" LINQ operator is used to filter elements in a collection based on a specified condition.
Scenario: Your WinForms application requires the user to edit and save customer information. How can you ensure that changes made in a data-bound control are propagated back to the data source?
- Implement the INotifyPropertyChanged interface
- Use the DataBindingComplete event
- Call the Update method of the data adapter
- Set the DataPropertyName property of the data-bound control
The correct option is Call the Update method of the data adapter. When working with data-bound controls in WinForms applications, changes made in the controls need to be saved back to the underlying data source. One way to achieve this is by calling the Update method of the data adapter associated with the data source. This method applies changes made in the data-bound controls to the database.
How can parameterized queries help prevent SQL injection attacks?
- By encrypting the SQL commands
- By restricting database access
- By separating data from SQL commands
- By using complex SQL queries
Parameterized queries help prevent SQL injection attacks by separating data from SQL commands. With parameterized queries, user inputs are treated as data rather than executable commands, reducing the risk of malicious SQL injection. Parameters act as placeholders for user-supplied values, preventing attackers from injecting SQL code into the query. This practice enhances security by ensuring that user input is sanitized and properly handled, mitigating the risk of unauthorized access or data manipulation.
A stored procedure is a precompiled ___________ of SQL statements.
- collection
- grouping
- sequence
- set
A stored procedure is a precompiled sequence of SQL statements that are stored in the database and can be executed by applications. They offer advantages such as improved performance as they are precompiled and cached, reducing parsing overhead. Additionally, they provide security by controlling access to data through parameterized queries.
In ADO.NET, what are the different ways to call a stored procedure?
- Call() method, Invoke() method, ExecuteProcedure() method, Run() method
- CommandText property, ExecuteNonQuery() method, ExecuteReader() method, ExecuteScalar() method
- ExecuteNonQuery() method, ExecuteScalar() method, ExecuteReader() method, Execute() method
- ExecuteStoredProc() method, ExecuteStoredProcedure() method, ExecuteSP() method, CallStoredProc() method
In ADO.NET, you can call a stored procedure using the ExecuteNonQuery() method to execute a command that doesn't return any result set, ExecuteScalar() method to execute a command that returns a single value, and ExecuteReader() method to execute a command that returns a result set. The Execute() method can also be used to execute any type of command.
Scenario: You are working on a project that involves querying a list of products based on their category. Which LINQ operator would you use to accomplish this task?
- Select
- Where
- OrderBy
- GroupBy
The correct option for querying a list of products based on their category is the Where operator. The Where operator is used to filter elements based on a specified condition, allowing you to retrieve only the products that belong to a specific category.
The DataList control provides built-in support for ________ rendering, making it suitable for complex layouts.
- Custom
- Grid
- List
- Table
The DataList control in ADO.NET provides built-in support for tabular rendering, which makes it suitable for displaying data in complex layouts resembling tables. This makes it easier for developers to arrange and present data in a structured format within their web applications.
What is the purpose of the "Include" method in Entity Framework?
- To filter the result set based on a condition
- To limit the number of records returned
- To perform inner joins between tables
- To specify which related entities should be retrieved
The "Include" method in Entity Framework is used to specify which related entities should be retrieved along with the main entity. This helps in eagerly loading related data, preventing the need for additional queries when accessing navigation properties. By including related entities, Entity Framework can retrieve all the necessary data in a single query, improving performance by reducing database round-trips. This method is particularly useful in scenarios where you need to access related data efficiently, such as when fetching data for complex reports or displaying detailed views.