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ConnectionStrings

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•   While developing any application that has to interact with the data source in order to retrieve,insert,update and delete the data from it, there are possibilities that a developer can make mistakes while establishing connection to the data source by hard coding the ConnectionString in the source code.

•      Hard coding such lines of code for an application consumes time and requires man power to make an application work perfectly if the application has many web pages or windows forms.

•        The developer has to connect the application to different data source in order to test it. In such situation, hard coding may lead to errors in the source code because we need to make changes for every ConnectionStrings in all web pages/windows forms for a single data source which is definitely error prone and time consuming.

•     So to overcome such situation, we have ConnectionStrings class where we place the code of the connection and give that connection; a meaningful name and use that name in all web pages/windows form in order to establish connection to the data source specified in the ConnectionStrings.

•       To store the connection string at a place we have got configuration file. We use web.config file for web application and app.config file for windows application.

•      These configuration files contain the name of the connection string which we can use in the web pages/ windows form to establish connection to the data source.

•         In configurationfile code section we have configuration section under which we use:-

              > name element to give a name to the connection string.
              > ConnectionString property to specify the server or system name, data source(database) name and the integrated security. 
                 We can even use the userid and password if we use the SQL Server authentication to establish connection.
              > We have provider name element to provide the name of the provider like SqlClient, Oracle etc.

  • Following lines of codes shows ConnectionStrings for both web.config and app.config configuration files:-


<configuration>
<connectionStrings>
<addname="MyDemo" 
connectionString="Data Source=testServer;Initial Catalog=demo;
        Integrated Security=SSPI;"
providerName="System.Data.SqlClient"/>
</connectionStrings>
</configuration>

•  After setting configuration files with the connection codes we need to make an application to read that code from the configuration file.

•     For this purpose, we first need to import the Configuration namespace which provides the necessary class and properties. We have ConfigurationManager class in this namespace which reads the connection code from the configuration file using its property called ConnectionStrings which we use to specify the name or index number of the connectionStrings associated with the required data source.

Note: To read about ConfigurationManager class click on this link: ConfigurationManager class

• We can have multiple connectionStrings inside the configuration file to manage connection to different data sources. ConfigurationManager class returns the connectionString as a string so we need to store it in a string variable as shown below:-

String cs = ConfigurationManager.ConnectionStrings[“MyDemo”].ConnectionString;

•     So in the future if we want that application to point to the different data source then we need to change only the name of the server and the data source.

•      The web.config file in web application gets added by default and the app.config file needs to be added explicitly.


That's it....Thanks for reading this post...






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