Scenario: Your application allows users to update their profile information in a database. Which ADO.NET command is suitable for updating existing records?
- SqlCommand.ExecuteNonQuery()
- SqlCommand.ExecuteQuery()
- SqlCommand.ExecuteScalar()
- SqlCommand.ExecuteXmlReader()
SqlCommand.ExecuteNonQuery() is used to execute non-query commands, including data manipulation language (DML) queries like UPDATE statements. This command is ideal for tasks that modify the database without returning any data, making it suitable for updating existing records.
Entity Framework Code-First approach allows you to define _______ in your code, and the database schema will be generated based on these classes.
- Attributes
- Constraints
- Entities
- Relationships
Entity Framework Code-First approach enables developers to define entities, which are the classes representing the data model, in their code. These entities contain properties that map to the database tables. By defining these entities, developers can specify the structure of the database schema, and Entity Framework will automatically generate the corresponding database based on these classes.
The ToTable() method on a DataView is used to create a new ___________ from the filtered data.
- DataAdapter
- DataSet
- DataTable
- DataView
The ToTable() method on a DataView is used to convert the filtered data into a new DataTable. This method enables you to extract the filtered data and work with it separately, perhaps for further processing or display purposes.
When should you use the INSERT command in ADO.NET?
- When you want to add new records to the database.
- When you want to execute a stored procedure.
- When you want to modify existing data in the database.
- When you want to retrieve data from the database.
You should use the INSERT command in ADO.NET when you want to add new records to a database table. It allows you to insert data into a specified table in the database.
Scenario: You are developing a web application and need to populate a DropDownList control with a list of product categories from a database. What steps would you take to achieve this?
- Use ADO.NET to retrieve data from the database and then loop through the results to populate the DropDownList control.
- Use Entity Framework to query the database and bind the results directly to the DropDownList control.
- Use LINQ to SQL to query the database and bind the results directly to the DropDownList control.
- Use a data source control like SqlDataSource to connect to the database and bind it to the DropDownList control.
Option 4 is the correct approach. SqlDataSource provides an efficient and easy way to connect to a database and bind data to a DropDownList control in ASP.NET applications. By configuring the SqlDataSource control with the appropriate SQL query or stored procedure, you can populate the DropDownList with product categories from the database. This approach also helps in maintaining separation of concerns by keeping data access logic separate from UI code.
What is the key difference between LINQ to Objects and LINQ to SQL in terms of data source?
- LINQ to Objects is more suitable for querying relational databases
- LINQ to Objects queries in-memory .NET collections
- LINQ to SQL operates on in-memory data structures
- LINQ to SQL queries databases using SQL
The key distinction lies in their data sources: LINQ to Objects operates on in-memory .NET collections like lists and arrays, while LINQ to SQL interacts with relational databases by generating and executing SQL queries.
How can you implement custom conflict resolution logic in ADO.NET?
- Implementing custom event handlers
- Modifying the ADO.NET configuration file
- Using built-in conflict resolution methods
- Using triggers in the database
Custom conflict resolution logic in ADO.NET can be implemented by creating custom event handlers for conflict-related events such as RowUpdating and RowUpdated, where developers can define specific actions to handle conflicts based on their application requirements.
LINQ to DataSet allows you to perform ___________ operations on grouped data.
- Aggregation
- Filtering
- Sorting
- Transformation
LINQ to DataSet enables you to perform aggregation operations on grouped data. This includes operations such as calculating counts, sums, averages, and other aggregate functions over the data within each group, providing powerful analytical capabilities.
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.
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: 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.
Connection pooling helps in efficiently managing and reusing database ___________.
- connections
- memory
- objects
- resources
Connection pooling in databases refers to the technique of reusing established connections instead of creating new ones, thereby optimizing resource utilization and enhancing performance. It manages the connections to the database, not just the memory or resources. Thus, "connections" is the correct option.