![Bulk Copy Operation
Datareader’s execute methods
Boxing- It is the process where a value type is converted into the type object.
Unboxing-It is the process where the value stored in an object is converted back to its original value type.
22. What is boxing and unboxing?
23. What is the purpose of the ExecuteScalar method of the SqlCommand object?
using System;
using System.Data;
using System.Data.SqlClient;
using System;
using System.Data;
using System.Data.SqlClient;
class Program
{
static void Main(string[] args)
{
object boxedInt = 123; // Boxing occurs here
Console.WriteLine("Type of boxedInt: " + boxedInt.GetType());
class Program
{
static void Main(string[] args)
{
object boxedInt = 123;
int unboxedInt = (int)boxedInt; // Unboxing occurs here
Console.WriteLine("Type of unboxedInt: " + unboxedInt.GetType());
}
SqlConnection connection = new SqlConnection("Your Connection String");
object boxedConnection = connection; // Boxing occurs here
Console.WriteLine("Type of boxedConnection: " + boxedConnection.GetType());
}
}
SqlConnection connection = new SqlConnection("Your Connection String");
object boxedConnection = connection;
SqlConnection unboxedConnection = (SqlConnection)boxedConnection; // Unboxing occurs here
Console.WriteLine("Type of unboxedConnection: " + unboxedConnection.GetType());
}](https://image.slidesharecdn.com/ado-250311210914-ed855651/85/ADO-NET-Interview-Questions-PDF-By-ScholarHat-5-320.jpg)
![29. What is the purpose of the SqlBulkCopy class in ADO.NET?
31. What is the purpose of the DbProviderFactory class in ADO.NET?
The DbProviderFactory class is used to create instances of ADO.NET data provider-specific classes such as
Connection, Command, DataReader, etc. without hardcoding dependencies on a specific data provider. It allows
applications to switch between different data providers like SQL Server, Oracle, and MySQL, without the need for
changing the code, making it more flexible and portable.
28. Explain the role of the SqlCommand.Transaction property in ADO.NET
transactions.
The SqlCommand.Transaction property is used to associate a SqlCommand object with a transaction that allows
multiple SQL commands to happen in the same transaction. It makes sure that all the commands being executed
with the help of the SqlCommand are included in the same transaction and that either all will succeed or they will
all fail as a unit, to maintain data consistency.
30. Explain the difference between optimistic concurrency and pessimistic
concurrency in ADO.NET.
32. Explain the concept of data binding in ADO.NET and how it is implemented.
Data binding in ADO.NET is the process where the data from a data source is connected with the controls on the
interface such as lists, forms, etc. This way changes made to the data are automatically reflected in the UI and
vice versa.
The SqlBulkCopy class is used to efficiently bulk insert large amounts of data into a SQL Server database.
It provides a high-performance mechanism for transferring data from a data source to a SQL Server table.
It is scalable and efficient, it bypasses the overhead of individual INSERT statements.
Optimistic Concurrency
It assumes that conflicts between concurrent
transactions are rare.
It lets multiple transactions read and modify the same
data simultaneously.
Pessimistic Concurrency
It assumes that conflicts between concurrent
transactions are a common thing.
It locks the data resources to prevent concurrent access.
class Program
{
static void Main(string[] args)
{
using System;
using System.Data;
using System.Data.SqlClient;
using System.Windows.Forms; // Required for WinForms data binding](https://image.slidesharecdn.com/ado-250311210914-ed855651/85/ADO-NET-Interview-Questions-PDF-By-ScholarHat-7-320.jpg)
![The SqlCommand.Parameters collection is used to specify parameterized values for SQL commands, allowing you to
pass parameters to SQL commands safely and securely. By using parameters instead of concatenating values directly
into the SQL string, you can prevent SQL injection attacks, as the parameter values are treated as data rather than
executable SQL code, making it difficult for attackers to manipulate the SQL command.
Here, we have created a DataSet and it is filled with data from an SQL query. This is done with the help of
SqlDataAdapter.
Stored procedures are precompiled SQL queries stored in the database and executed by calling their names from
ADO.NET code. They offer several advantages, including improved performance due to precompilation and
caching, enhanced security by preventing SQL injection attacks, and encapsulation of business logic within the
database for better maintainability and reusability.
34. Explain the concept of stored procedures in the context of ADO.NET.
33. How is SqlCommand.Parameters collection used to prevent SQL injection
attacks?
// Fill the DataSet with data from the database
adapter.Fill(dataSet, "YourTable");
string connectionString = "Your Connection String";
string query = "SELECT * FROM YourTable";
// Example: Binding to a ListBox in a Windows Forms application
ListBox listBox = new ListBox();
listBox.DataSource = dataSet.Tables["YourTable"];
listBox.DisplayMember = "ColumnNameToDisplay";
}
// Example: Binding to a ComboBox in a Windows Forms application
ComboBox comboBox = new ComboBox();
comboBox.DataSource = dataSet.Tables["YourTable"];
comboBox.DisplayMember = "ColumnNameToDisplay";
comboBox.ValueMember = "ColumnNameForValue";
}
}
using (SqlConnection connection = new SqlConnection(connectionString))
{
SqlDataAdapter adapter = new SqlDataAdapter(query, connection);
DataSet dataSet = new DataSet();
// Example: Binding to a DataGridView in a Windows Forms application
DataGridView dataGridView = new DataGridView();
dataGridView.DataSource = dataSet.Tables["YourTable"];](https://image.slidesharecdn.com/ado-250311210914-ed855651/85/ADO-NET-Interview-Questions-PDF-By-ScholarHat-8-320.jpg)
ADO.NET Interview Questions PDF By ScholarHat
- 1. Top 50 ADO.NET Most Important Interview Questions ADO.NET Interview Questions and Answers ADO.NET is a technology used for accessing and managing data when working in the field of .NET development. This is a vital component of .NET Framework which helps to ensure consistent access to data sources like SQL Server and XML. ADO.NET Interview Questions & Answers for Beginners 1. What is ADO.NET? ADO.NET stands for ActiveX Data Object. ADO.NET is a part of the .NET Framework which is used to provide database access in the .NET applications. It helps in accessing data and creating a link to interact between the data and data services. There are two types of architecture provided by ADO.NET that are: In this ASP.NET Tutorial, we will have a look at the most important ADO.NET Interview Questions and Answers. We have categorized them into ADO.NET Interview Questions for Freshers and ADO.NET Interview Questions for Experienced. Learn more about various concepts of ASP.NET through this guide to ASP.NET Certification Training. 2. Explain the types of architectures in ADO.NET.
- 2. The main components of ADO.NET include: Connection, Command, DataReader, DataSet, and Some of the key namespaces in ADO.NET are: System.Data System.Data.SqlClient System.Data.OleDb System.Data.Odbc System.Data.Common System.Data.EntityClient The data providers in ADO.NET are as follows: OLEDB MS SQL Server ODBC There are mainly two objects of ADO.NET that are: 1. DataSet 2. DataReader A linked server gives the ability to the SQL Server to read data from the remote data sources. Then the commands are executed on remote databases. 1. Connected Architecture-Connected architecture is the architecture where the connection is active throughout the operation. 2. Disconnected Architecture-In disconnected architecture, when there is a need to fetch or update data from the database, only at that time does the connection to the database open. LINQ is also known as Language Integrated Query. It is a native query language, typically used for managing queries with .NET applications. It allows developers to write queries directly within their C# or VB.NET code. 7. What is a linked server? 3. Name the ADO.NET objects? 5. Explain the term LINQ to ADO.NET. 4. What are the ADO.NET Namespaces? 6. Name the data providers in ADO.NET? 8. What are the main components of ADO.NET?
- 3. DataAdapter. DataReader A DataReader is a read-only, forward-only cursor that retrieves data from the database. It has limited functionality as compared to DataSet. DataSet A DataSet is an in-memory cache of data retrieved from the database. It allows the manipulation of complex data as well. A DataAdapter in ADO.NET is used to fill up a DataSet with data and update the data source with the help of command objects. SqlCommand is a class in ADO.NET and it helps in the execution of SQL commands in a SQL Server database. The various SQL commands are as follows: SELECT INSERT UPDATE DELETE. Connection Pooling, in ADO.NET, is a feature that lets you reuse existing connections from a pool of connections. This means, there is no need to create new connections every time a connection to the database is requested. The connection object in ADO.NET helps in setting up a connection to a data source like a database and manages it as well. 10. What is DataAdapter in ADO.NET? 12. Explain SqlCommand and its usage. 13. What is Connection Pooling in ADO.NET? 14. Explain the role of the DataAdapter.Fill method. 9. Explain the purpose of the Connection object in ADO.NET. 11. Differentiate between DataReader and DataSet in ADO.NET.
- 4. ADO.NET offers several features that include: New Data Controls Data Paging The several execution methods of ADO.NET are as follows: ExecutenonQuery ExecuteScalar ExecuteXMLReader ExecuteReader DataSet It is an in-memory data cache retrieved from a data source. It can hold multiple DataTables. The default timer is 30 seconds for SqlCommand.CommandTimeout property. A connection object in ADO.NET is used for setting up a connection between the data source and the application. DataTable It is a single table of data. It is a table with rows and columns within a DataSet. In object pooling, the objects in the memory are stored so that they can be used later which helps in reducing the load of creating an object every time it is required. The DataAdapter has a Fill method which is used to read the data from the data source into the DataSet and create DataTables that will hold the data. The data is stored in the DataTable based on the schema of the data returned by the SelectCommand. ADO.NET has many new features such as connection pooling, disconnected data access, etc which makes it better in comparison with ADO. With the help of ADO.NET, working with XML data and integration with .NET framework is easier. 18. What is object pooling? 21. Name the features of ADO.Net? 20. What is the use of a connection object? 15. How is a DataSet different from a DataTable? 19. What are the several execution methods of ADO.NET? 16. What are the advantages of using ADO.NET over classic ADO? 17. What is the default timeout stated for the "SqlCommand.CommandTimeout" proper ty? public int Fill(DataSet dataSet, string tableName);
- 5. Bulk Copy Operation Datareader’s execute methods Boxing- It is the process where a value type is converted into the type object. Unboxing-It is the process where the value stored in an object is converted back to its original value type. 22. What is boxing and unboxing? 23. What is the purpose of the ExecuteScalar method of the SqlCommand object? using System; using System.Data; using System.Data.SqlClient; using System; using System.Data; using System.Data.SqlClient; class Program { static void Main(string[] args) { object boxedInt = 123; // Boxing occurs here Console.WriteLine("Type of boxedInt: " + boxedInt.GetType()); class Program { static void Main(string[] args) { object boxedInt = 123; int unboxedInt = (int)boxedInt; // Unboxing occurs here Console.WriteLine("Type of unboxedInt: " + unboxedInt.GetType()); } SqlConnection connection = new SqlConnection("Your Connection String"); object boxedConnection = connection; // Boxing occurs here Console.WriteLine("Type of boxedConnection: " + boxedConnection.GetType()); } } SqlConnection connection = new SqlConnection("Your Connection String"); object boxedConnection = connection; SqlConnection unboxedConnection = (SqlConnection)boxedConnection; // Unboxing occurs here Console.WriteLine("Type of unboxedConnection: " + unboxedConnection.GetType()); }
- 6. ADO.NET transactions support different isolation levels that include: ReadUncommitted ReadCommitted RepeatableRead Serializable Snapshot A DbConnection is an abstract base class in ADO.NET. It represents a connection to a data source and provides a common set of methods and properties that help to manage connections and allow for a consistent programming interface across different data providers. Parameterized queries are just like normal commands. But they use placeholders in SQL commands instead of concatenating values directly into the SQL string, for values that will be given at runtime. Parameterized queries are important in the following ways: They help in the prevention of SQL injection attacks Improves the performance by allowing query plan reuse They can handle data type conversions automatically. The ExecuteScalar method of the SqlCommand object is used to execute an SQL query that will return a single value. It can be an aggregate function like COUNT, SUM, etc., and then it retrieves the result as an object. It is commonly used for queries that return a single value, such as obtaining the count of records in a table. A SqlParameter is a class in ADO.NET that is used to represent parameters in SQL commands. With SqlParameter, there is no need to concatenate strings and you can easily pass parameters to SQL commands. It also provides type safety. 25. What is a DbConnection and why is it used? 24. What is a SqlParameter and why is it important? 26. Explain the concept of parameterized queries in ADO.NET and why they are important. 27. What are the different isolation levels supported by ADO.NET transactions? ADO.NET Interview Questions and Answers for Intermediate
- 7. 29. What is the purpose of the SqlBulkCopy class in ADO.NET? 31. What is the purpose of the DbProviderFactory class in ADO.NET? The DbProviderFactory class is used to create instances of ADO.NET data provider-specific classes such as Connection, Command, DataReader, etc. without hardcoding dependencies on a specific data provider. It allows applications to switch between different data providers like SQL Server, Oracle, and MySQL, without the need for changing the code, making it more flexible and portable. 28. Explain the role of the SqlCommand.Transaction property in ADO.NET transactions. The SqlCommand.Transaction property is used to associate a SqlCommand object with a transaction that allows multiple SQL commands to happen in the same transaction. It makes sure that all the commands being executed with the help of the SqlCommand are included in the same transaction and that either all will succeed or they will all fail as a unit, to maintain data consistency. 30. Explain the difference between optimistic concurrency and pessimistic concurrency in ADO.NET. 32. Explain the concept of data binding in ADO.NET and how it is implemented. Data binding in ADO.NET is the process where the data from a data source is connected with the controls on the interface such as lists, forms, etc. This way changes made to the data are automatically reflected in the UI and vice versa. The SqlBulkCopy class is used to efficiently bulk insert large amounts of data into a SQL Server database. It provides a high-performance mechanism for transferring data from a data source to a SQL Server table. It is scalable and efficient, it bypasses the overhead of individual INSERT statements. Optimistic Concurrency It assumes that conflicts between concurrent transactions are rare. It lets multiple transactions read and modify the same data simultaneously. Pessimistic Concurrency It assumes that conflicts between concurrent transactions are a common thing. It locks the data resources to prevent concurrent access. class Program { static void Main(string[] args) { using System; using System.Data; using System.Data.SqlClient; using System.Windows.Forms; // Required for WinForms data binding
- 8. The SqlCommand.Parameters collection is used to specify parameterized values for SQL commands, allowing you to pass parameters to SQL commands safely and securely. By using parameters instead of concatenating values directly into the SQL string, you can prevent SQL injection attacks, as the parameter values are treated as data rather than executable SQL code, making it difficult for attackers to manipulate the SQL command. Here, we have created a DataSet and it is filled with data from an SQL query. This is done with the help of SqlDataAdapter. Stored procedures are precompiled SQL queries stored in the database and executed by calling their names from ADO.NET code. They offer several advantages, including improved performance due to precompilation and caching, enhanced security by preventing SQL injection attacks, and encapsulation of business logic within the database for better maintainability and reusability. 34. Explain the concept of stored procedures in the context of ADO.NET. 33. How is SqlCommand.Parameters collection used to prevent SQL injection attacks? // Fill the DataSet with data from the database adapter.Fill(dataSet, "YourTable"); string connectionString = "Your Connection String"; string query = "SELECT * FROM YourTable"; // Example: Binding to a ListBox in a Windows Forms application ListBox listBox = new ListBox(); listBox.DataSource = dataSet.Tables["YourTable"]; listBox.DisplayMember = "ColumnNameToDisplay"; } // Example: Binding to a ComboBox in a Windows Forms application ComboBox comboBox = new ComboBox(); comboBox.DataSource = dataSet.Tables["YourTable"]; comboBox.DisplayMember = "ColumnNameToDisplay"; comboBox.ValueMember = "ColumnNameForValue"; } } using (SqlConnection connection = new SqlConnection(connectionString)) { SqlDataAdapter adapter = new SqlDataAdapter(query, connection); DataSet dataSet = new DataSet(); // Example: Binding to a DataGridView in a Windows Forms application DataGridView dataGridView = new DataGridView(); dataGridView.DataSource = dataSet.Tables["YourTable"];
- 9. 39. What are the ADO.NET connection pooling parameters 38. What is Entity Framework, and how does it relate to ADO.NET? Entity Framework is an ORM framework, also known as Object-Relational Mapping. It is a part of the .NET framework that the developers use for working with relational data using objects and queries. 37. Discuss the benefits of using asynchronous programming techniques in ADO.NET applications. Asynchronous Programming techniques in ADO.NET applications are beneficial in many ways such as: 35. What is the purpose of the DbDataReader class in ADO.NET, and how does it differ from other data reader classes? The DbDataReader class is a base class for data readers that retrieve data from a data source in a forward-only, read- only manner. It differs from other data reader classes (such as SqlDataReader for SQL Server or OleDbDataReader for OLE DB) in that it provides a common programming interface across different data providers, allowing for database- agnostic code. 36. Explain the purpose of the DbCommandTimeout property in ADO.NET and how it can be used to improve application performance. The DbCommandTimeout property is used to specify the maximum amount of time (in seconds) that a command can execute before it times out and generates an exception. It can be used to prevent long-running queries from blocking the application and causing performance degradation by setting an appropriate timeout value based on the expected execution time of the command. 1. Connection Timeout-Its default value is 15. 2. Connection Lifetime-Its default value is 0. 3. Min Pool Size-Its default value is 0. 4. Max Pool Size- Its default value is 100. 5. Incr Pool Size-Its default value is 5. It allows applications to perform I/O-bound operations such as database queries, asynchronously. It does not block the main thread which is better for its responsiveness. It allows the application to continue executing other tasks while it waits for the operation to complete using the async/await keywords in C#.
- 10. . Decr Pool Size-Its default value is 1. 7. Pooling- Its default values are true. There are mainly two classes in System.Data.Common Namespace that are: 1. DataColumnMapping 2. DataTableMapping ADO.NET applications can handle transactions using different strategies such as: Implicit Transactions-Using the auto-commit mode. Explicit Transactions-Using the BeginTransaction and Commit/Rollback methods. Distributed Transactions-Using the TransactionScope. Lightweight Transactions-Using the optimistic concurrency control. The various methods of an XML dataset object are as follows: WriteXml()-It is used to copy all the content of the dataset to a file. WriteXmlSchema()-It is used to copy the XSD schema into a file. GetXml()-It is used to receive the XML data in a dataset as a single string. GetXmlSchema()-It is used to receive the XSD schema in a dataset as a single string. ReadXml()-It is used to read the XML data from a file. ReadXmlSchema()-It is used to read the XML schema from a file. Dataset.clone It only copies the structure of the dataset. Dataset.copy It copies both the structure and the data from the table. It creates a new empty dataset with tables and columns. It will create a new dataset with table, columns, rows as well. Execute Scalar method is the method used by the command class to execute SQL statements that return single value. 41. What are the methods of an XML dataset object? 44. What are the classes in System.Data.Common Namespace? 40. What is the difference between Dataset.clone and Dataset.copy? 42. Discuss the different strategies for handling transactions in ADO.NET applications. 43. Name the method that the command class uses to execute SQL statements that return a single value? 45. Discuss the benefits and limitations of using stored procedures vs. dynamic SQL in ADO.NET applications. ADO.NET Interview Questions and Answers for Experienced
- 11. Benefits of: Limitations of: Some of the best practices for managing and securing connection strings are as follows: Use encrypted configuration files or secure storage mechanisms to store them securely. Try to avoid hardcoding sensitive information. Use connection string builders for constructing connection strings dynamically. Minimize the scope and lifetime of connections. We can use the Thread.Abort() function when we want to stop the thread from executing at any time. Stored Procedures-It has several benefits that include precompilation and caching, prevention from SQL injection attacks, and encapsulation of business logic within the database. Dynamic SQL- It provides benefits such as flexibility in constructing queries dynamically at runtime. Connection strings are used to specify the information needed to establish a connection to a data source. The connection includes the database server address, authentication credentials, and database name. A DataRelation class uses DataColumn objects and relates two DataTable objects to each other. It is a class of disconnected architecture in the .NET framework and present in the System.Data namespace. These questions covered various topics from ADO.NET that will help you ace your next interview as a fresher or professional ASP.NET developer. To learn more about different concepts of .NET development, consider enrolling in our ASP.NET Certification Course and start your tech career the right way! The HasChanges() method of DataSet returns a boolean value that shows if the record DataSet has been successfully changed or not. If the changes were successfully made, it will return true but if there were no changes made, it will return false. Stored Procedures-It is not portable enough for different database platforms, less flexible for dynamic queries, and more complex in versioning and maintenance. Dynamic SQL-It is less secure from SQL injection attacks, and query plan generation creates performance overhead. 49. How to stop thread running? 50. What is the HasChanges() method of DataSet? 46. What do you understand from the DataRelation class? 47. What is the role of connection strings in ADO.NET applications? 48. Discuss some of the best practices for managing and securing connection strings. Summary