ADO.NET - .NET Interview Questions and Answers

The following are the usages of the Command object in AD0.NET:

The Command object in AD0.NET 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.
  
  

The prerequisites for connection pooling are as follows:

• There must be multiple processes to share the same connection describing the same parameters and security settings.
• The connection string must be identical.

Connection pooling refers to the task of grouping database connections in cache to make them reusable because opening new connections every time to a database is a time-consuming process. Therefore, connection pooling enables you to reuse already existing and active database connections, whenever required, and increasing the performance of your application.

You can enable or disable connection pooling in your application by setting the pooling property to either true or false in connection string. By default, it is enabled in an application.

The various methods provided by the DataSet object to generate XML are:

• ReadXml() - Reads XML document into a DataSet object.
• GetXml() - Returns a string containing an XML document.
• WriteXml() - Writes an XML data to disk.

The Windows authentication technique is considered as a trusted authentication method because the username and password are checked with the Windows credentials stored in the Active Directory.

The SQL Server Authentication technique is not trusted as all the values are verified by SQL Server only.

The connection class is used to connect a .NET application with a database.