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.
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.
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.
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.
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.
DataViews are particularly useful when you want to present a ___________ of your data to the user.
- Sorted view
- Filtered view
- Virtualized view
- Customized view
DataViews in ADO.NET are versatile tools for data manipulation. They allow you to present a customized view of your data to the user. This can include sorting, filtering, and applying custom logic to the data, hence "Customized view" is the correct option.
Scenario: You need to retrieve data from an XML document. Which LINQ technology can be used for querying XML data?
- LINQ to Entities
- LINQ to Objects
- LINQ to SQL
- LINQ to XML
LINQ to XML is designed for querying and manipulating XML data. It allows developers to write LINQ queries against XML documents, providing a convenient and expressive way to extract and process XML data.
What is the key difference between a SqlDataReader and an OracleDataReader?
- SqlDataReader is a class in the System.Data.SqlClient namespace, whereas OracleDataReader is a class in the System.Data.OracleClient namespace.
- SqlDataReader is forward-only, whereas OracleDataReader allows both forward and backward data access.
- SqlDataReader is specific to SQL Server databases, whereas OracleDataReader is specific to Oracle databases.
- SqlDataReader is used for reading data from XML files, whereas OracleDataReader is used for reading data from Oracle databases.
SqlDataReader and OracleDataReader are specific to their respective database systems and differ in their namespaces and database compatibility.
A SqlDataReader provides a forward-only, ___________ way to read data from a database.
- Bidirectional
- Random Access
- Sequential
- One-way
The correct option is Option 3: Sequential. A SqlDataReader provides a forward-only, sequential way to read data from a database. It can only move in one direction, typically from the first row to the last, and cannot jump to specific rows or move backward.
SQL injection attacks occur when malicious users exploit vulnerabilities in ___________ statements.
- DELETE
- INSERT
- SELECT
- UPDATE
SQL injection attacks occur when attackers manipulate the input of SQL queries to execute arbitrary commands. The vulnerability often lies in poorly sanitized user inputs, especially in SELECT statements, allowing unauthorized access to data.
What does data concurrency refer to in the context of ADO.NET?
- The ability of multiple users to access and manipulate the same data simultaneously.
- The method of securing data during transmission over a network.
- The process of ensuring data consistency within a database.
- The technique of optimizing database queries for faster performance.
Data concurrency in ADO.NET refers to the ability of multiple users to access and manipulate the same data simultaneously without interfering with each other's changes. This is important in scenarios where multiple users may be accessing and modifying data concurrently, such as in a multi-user database system.
Scenario: You are tasked with implementing a hierarchical view of data, where each employee has associated orders. Which ADO.NET data binding approach would you choose for this task?
- DataSet with DataRelation
- DataReader with multiple queries
- Entity Framework
- DataAdapter with JOIN queries
The correct option is DataSet with DataRelation. A DataSet with DataRelation allows you to represent hierarchical data structures easily. By defining a relationship between the employee and order tables using DataRelation, you can create a hierarchical view where each employee has associated orders. DataReader with multiple queries might work but can be complex to manage and maintain. Entity Framework is an ORM for database interactions and might not directly represent hierarchical data. DataAdapter with JOIN queries can retrieve related data but might not provide a straightforward hierarchical structure.