ADO .Net – Introduction


  • ADO.NET is a module of .Net Framework which is used to establish connection between application and data sources.
  • Data sources can be such as SQL Server and XML. ADO.NET consists of classes that can be used to connect, retrieve, insert and delete data.

.NET Framework Data Providers

  • These are the components that are designed for data manipulation and fast access to data.
  • It provides various objects such as Connection, Command, DataReader and DataAdapter that are used to perform database operations.
  • The .NET Framework Data Provider for SQL Server classes is located in the System.Data.SqlClient namespace.
  • We can include this namespace in our C# application by using the following syntax.
    • using System.Data.SqlClient; 

This namespace contains the following important classes.

SqlConnectionIt is used to create SQL Server connection. This class cannot be inherited.
SqlCommandIt is used to execute database queries. This class cannot be inherited.
SqlDataAdapterIt represents a set of data commands and a database connection that are used to fill the DataSet. This class cannot be inherited.
SqlDataReaderIt is used to read rows from a SQL Server database. This class cannot be inherited.
SqlExceptionThis class is used to throw SQL exceptions. It throws an exception when an error is occurred. This class cannot be inherited.

ADO.NET SqlConnection Class

  • It is used to establish an open connection to the SQL Server database.
  • It is a sealed class so that cannot be inherited.
  • Connection does not close explicitly even it goes out of scope.
  • Therefore, you must explicitly close the connection by calling Close() method.

SqlConnection Constructors

SqlConnection()It is used to initializes a new instance of the SqlConnection class.
SqlConnection(String)It is used to initialize a new instance of the SqlConnection class and takes connection string as an argument.

SqlConnection Methods

BeginTransaction()It is used to start a database transaction.
ChangeDatabase(String)It is used to change the current database for an open SqlConnection.
ChangePassword(String, String)It changes the SQL Server password for the user indicated in the connection string.
Close()It is used to close the connection to the database.
CreateCommand()It enlists in the specified transaction as a distributed transaction.
GetSchema()It returns schema information for the data source of this SqlConnection.
Open()It is used to open a database connection.
ResetStatistics()It resets all values if statistics gathering is enabled.

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