What are the usages of the Command object in ADO.NET?

Correct Answer: The following are the usages of the Command object in AD0NET: The Command object in AD0NET executes a command against the database and retrieves a DataReader or DataSet object => It also executes the INSERT, UPDATE, or DELETE command against the database => All the command objects are derived from the DbCommand class => The command object is represented by two classes: SqlCommand and OleDbCommand => The Command object provides three methods to execute commands on the database: => The ExecuteNonQuery() method executes the commands and does not return any value => The ExecuteScalar() method returns a single value from a database query => The ExecuteReader() method returns a result set by using the DataReader object

Correct Answer: ADONET is a very important feature of NET Framework, which is used to work with data that is stored in structured data sources, such as databases and XML files The following are some of the important features of ADONET: => Contains a number of classes that provide you with various methods and attributes to manage the communication between your application and data source => Enables you to access different data sources, such as Microsoft SQL Server, and XML, as per your requirements => Provides a rich set of features, such as connection and commands that can be used to develop robust and highly efficient data services in NET applications => Provides various data providers that are specific to databases produced by various vendors For example, ADONET has a separate provider to access data from Oracle databases; whereas, another provider is used to access data from SQL databases

Correct Answer: You can prevent a class from overriding in C# by using the sealed keyword; whereas, the NotInheritable keyword is used to prevent a class from overriding in Visual Basic

Correct Answer: When a class is derived from another class, then the members of the base class become the members of the derived class The access modifier used while accessing members of the base class specifies the access status of the base class members inside the derived class The syntax to inherit a class from another class in C# is as follows: class MyNewClass : MyBaseclass

Correct Answer: NET does not support multiple inheritance directly because in NET, a class cannot inherit from more than one class NET supports multiple inheritance through interfaces

Correct Answer: DLR is a runtime environment that allows you to integrate dynamic languages with the Common Language Runtime (CLR) by adding a set of services, such as expression trees, call site caching, and dynamic object interoperability to the CLR The SystemDynamic and SystemRuntimeCompilerServices namespaces are used to hold the classes for DLR It also provides dynamic features to statically-typed languages, such as C# and Visual Basic to enable their interoperation with dynamic languages

Correct Answer: ASPNET is a specification developed by Microsoft to create dynamic Web applications, Web sites, and Web services It is a part of NET Framework You can create ASPNET applications in most of the NET compatible languages, such as Visual Basic, C#, and J# The ASPNET compiles the Web pages and provides much better performance than scripting languages, such as VBScript The Web Forms support to create powerful forms-based Web pages You can use ASPNET Web server controls to create interactive Web applications With the help of Web server controls, you can easily create a Web application

Correct Answer: The basic difference between ASP and ASPNET is that ASP is interpreted; whereas, ASPNET is compiled This implies that since ASP uses VBScript; therefore, when an ASP page is executed, it is interpreted On the other hand, ASPNET uses NET languages, such as C# and VBNET, which are compiled to Microsoft Intermediate Language (MSIL)

Correct Answer: You can use the SystemNetMailMailMessage and the SystemNetMailSmtpMail classes to send an email in your Web pages In order to send an email through your mail server, you need to create an object of the SmtpClient class and set the server name, port, and credentials

Correct Answer: The code-behind feature of ASPNET enables you to divide an ASPNET page into two files - one consisting of the presentation data, and the second, which is also called the code-behind file, consisting of all the business logic The presentation data contains the interface elements, such as HTML controls and Web server controls, and the code-behind contains the event-handling process to handle the events that are fired by these controls The file that contains the presentation data has the aspx extension The code behind file has either the cs extension (if you are using the programming language C#) or the vb (if you are using the programming language Visual Basic NET) extension