![<connectionStrings>
<add name="PubsData“ providerName="System.Data.SqlClient"
connectionString= "Data Source=.SQLEXPRESS;
AttachDbFilename=|DataDirectory|PUBS.MDF; Integrated
Security=True; User Instance=True"/>
</connectionStrings>
ConnectionStringSettings pubs =
ConfigurationManager.ConnectionStrings["PubsData"];
DbConnection connection = new SqlConnection(pubs.ConnectionString);](https://image.slidesharecdn.com/connecteddataclasses-120206052513-phpapp02/85/Connected-data-classes-13-320.jpg)
Connected data classes
- 2.  DbConnection  DbCommand  DbDataReader  DbDataAdapter  DbProviderFactory
- 3.  The classes that are responsible for working with the database for connecting, retrieving, updating, inserting, and deleting data are referred to as provider classes in the framework.  The ADO.NET libraries contain provider classes, which are classes that you can use to transfer data between a data store and the client application.  The Microsoft .NET Framework contains the following data access providers:  OleDb  Odbc  SqlServer  Oracle
- 5.  To access a data store, you need a valid, open connection object.  The DbConnection class is an abstract class from which the provider-specific connection classes inherit.  To create a connection, you must have a valid connection string. DbConnection connection = new SqlConnection(); connection.ConnectionString = "Server=.;Database=pubs;Trusted_Connection=true"; connection.Open(); //do work here connection.Close();
- 6. Open Database Connectivity (ODBC) is one of the older technologies that the .NET Framework supports, primarily because there are still many scenarios in which the .NET Framework is required to connect to older database products that have ODBC drivers.
- 7.  Driver={Microsoft Text Driver (*.txt; *.csv)}; DBQ=C:SampleMySampleFolder;  Driver={Microsoft Access Driver (*.mdb)}; DBQ=C:CodemySampleFoldernorthwind.mdb  Driver={Microsoft ODBC for Oracle}; Server=ORACLE8i7; UID=john; PWD=s3$W%1Xz  Driver={Microsoft Excel Driver (*.xls)}; DBQ=C:SamplesMyBook.xls  DRIVER={SQL Server}; SERVER=MyServer; UID=AppUserAccount; PWD=Zx%7$ha; DATABASE=northwind;
- 8. Another common, but older, technology that is used to access databases is Object Linking and Embedding for Databases (OLEDB).
- 9. This connection string uses the settings stored in the MyAppData.udl file (the .udl extension stands for universal data link): FILE NAME=C:Program FilesMyAppMyAppData.udl This connection string uses the Jet driver, which is the Access driver, and opens the demo.mdb database file. Provider=Microsoft.Jet.OLEDB.4.0; Data Source=C:Program FilesmyAppdemo.mdb; Persist Security Info=False
- 12. Persist Security Info=False; Integrated Security=SSPI; database=northwind; Network Library=DBMSSOCN; Data Source=192.168.1.5,1433; Initial Catalog=MyDbName; User ID=myUsername; Password= u$2hJq@1 Data Source=.SQLEXPRESS; AttachDbFilename=C:MyApplicationPUBS.MDF; Integrated Security=True; User Instance=True
- 13. <connectionStrings> <add name="PubsData“ providerName="System.Data.SqlClient" connectionString= "Data Source=.SQLEXPRESS; AttachDbFilename=|DataDirectory|PUBS.MDF; Integrated Security=True; User Instance=True"/> </connectionStrings> ConnectionStringSettings pubs = ConfigurationManager.ConnectionStrings["PubsData"]; DbConnection connection = new SqlConnection(pubs.ConnectionString);
- 14.  Connection pooling is the process of reusing existing active connections instead of creating new connections when a request is made to the database.  It involves the use of a connection manager that is responsible for maintaining a list, or pool, of available connections.  When the connection manager receives a request for a new connection, it checks its pool for available connections. If a connection is available, it is returned.  If no connections are available, and the maximum pool size has not been reached, a new connection is created and returned.  If the maximum pool size has been reached, the connection request is added to the queue and the next available connection is returned, as long as the connection timeout has not been reached.
- 15. Connection pooling is controlled by parameters placed into the connection string. The following is a list of parameters that affect pooling:  Connection Timeout  Min Pool Size  Max Pool Size  Pooling  Connection Reset  Load Balancing Timeout, Connection Lifetime  Enlist
- 16.  The DbCommand object is used to send one or more Structured Query Language (SQL) statements to the data store.  The DbCommand can be any of the following types:  Data Manipulation Language (DML) Commands that retrieve, insert, update, or delete data  Data Definition Language (DDL) Commands that create tables or other database objects, or modify the database schema  Data Control Language (DCL) Commands that grant, deny, or revoke permissions