Scenario: You are binding data to a DropDownList in an ASP.NET application, and you want to ensure that the selected item's value is accessible on the server-side during postback. What properties and events should you consider?
- Set the AutoPostBack property of the DropDownList control to true and handle the SelectedIndexChanged event.
- Set the EnableViewState property of the DropDownList control to false.
- Use JavaScript to update a hidden field with the selected item's value on the client-side.
- Set the CausesValidation property of the DropDownList control to true and handle the ServerValidate event.
Option 1 is the correct approach. By setting the AutoPostBack property of the DropDownList control to true, you ensure that a postback occurs whenever the selection changes. This allows you to handle the SelectedIndexChanged event on the server-side, where you can access the selected item's value using the DropDownList's SelectedValue property. This approach ensures that the selected item's value is available for processing during postback.
Scenario: In a LINQ query, you encounter the orderby clause. What is the purpose of this clause, and how does it affect the query results?
- It filters the elements based on a specified condition.
- It groups the elements based on a common key.
- It joins two or more collections based on a related key.
- It sorts the elements in ascending order based on a specified key.
The purpose of the orderby clause in a LINQ query is to sort the elements in ascending order based on a specified key. This clause arranges the query results alphabetically or numerically according to the specified key, allowing for organized presentation of data.
Scenario: A colleague suggests using plain SQL statements instead of parameterized queries for simplicity. What would you advise them regarding SQL injection risks?
- Advise against using plain SQL statements
- Encourage using input validation
- Recommend using stored procedures
- Suggest using a web application firewall
Using plain SQL statements exposes the application to SQL injection vulnerabilities. Parameterized queries provide a more robust defense against such attacks. Recommending stored procedures can be a good practice, but it's not as directly related to preventing SQL injection as parameterized queries. Web application firewalls and input validation are important layers of defense but should not replace proper SQL injection prevention measures.
Which ADO.NET feature helps in managing data conflicts during concurrent data access?
- Data Adapter
- Data Reader
- Data Set
- Data Table
ADO.NET Data Set helps in managing data conflicts during concurrent data access. It can store multiple DataTable objects along with relationships, providing a disconnected representation of the data from the data source. This enables offline manipulation of data and conflict resolution before updating the data source.
In WinForms, what is the difference between one-way and two-way data binding?
- One-way data binding allows data modification only through UI controls
- One-way data binding updates the UI controls when the data source changes
- Two-way data binding requires explicit synchronization between UI and data source
- Two-way data binding updates the data source when the UI controls are modified
One-way data binding updates the UI controls when the data source changes, whereas two-way data binding facilitates bidirectional synchronization, updating the data source when the UI controls are modified and vice versa. This difference is crucial in scenarios where real-time data updates are necessary.
When working with a ListBox control, you can use the ___________ property to set the data field that serves as the value for each item.
- DataTextField
- DataValueField
- DataSource
- DataMember
The correct option is 2. DataValueField. This property is used to set the data field that serves as the value for each item in a ListBox control. It is essential for data binding and displaying meaningful values to users.
To customize the appearance of cells, you can handle the "___________" event.
- CellClick
- CellFormatting
- DataBindingComplete
- RowValidating
To customize the appearance of cells, you can handle the "CellFormatting" event. This event allows you to modify the visual presentation of individual cells in a DataGridView or DataGrid control based on specified conditions, such as data values or cell locations.
What is the key difference between DataGrid and DataGridView controls?
- Color scheme
- Licensing cost
- Platform dependency
- Supported features
The key difference between DataGrid and DataGridView controls lies in the supported features. DataGrid is the older control available in Windows Forms, offering basic functionalities for displaying data. DataGridView, introduced in .NET Framework 2.0, provides enhanced features such as data binding, sorting, filtering, and editing capabilities, making it more versatile and powerful compared to DataGrid.
When working with ADO.NET data binding, the DataBinder class provides methods for ___________ data presentation.
- Formatting
- Validating
- Binding
- Displaying
The DataBinder class in ADO.NET provides methods for binding data to controls, ensuring seamless data presentation. Therefore, the correct option is "Binding".
Scenario: You are working with an Oracle database and need to handle NULL values gracefully while reading data. Which method of the OracleDataReader would you use for this purpose?
- GetOracleValue()
- GetString()
- GetValue()
- IsDBNull()
The IsDBNull() method of the OracleDataReader class allows for the graceful handling of NULL values in an Oracle database. It returns true if the specified column contains a NULL value, enabling developers to handle NULLs appropriately in their application logic. GetValue() retrieves the value of the specified column, GetString() returns the value of the specified column as a string, and GetOracleValue() is not a valid method in OracleDataReader.