Connection String in ASP.NET With SQL Server

Connection string can be placed in web.config file found in root directory of the application from .NET 3.5 onward.
connection string can be specified with an xml tag <connectionStrings> inside <configuration> section of web.config file.

<connectionStrings> <add name="myConnectionString"
connectionString="Data Source=databaseServerName;
database=database-name;
uid=sqlUserName;password=sqlPassword;
Integrated Security=True|false|SSPI (any one options) ;"
providerName="System.Data.SqlClientSystem.Data.SqlClient" />
</connectionStrings>

We can use local database server of SQL Server by using
Data Source=(LocalDb)\MSSQLLocalDB
we can attach a local database file to the app_data directory by using the property
AttachDBFilename=|DataDirectory|\appDatabaseName.mdf in the connection string

Connection String can be accessed in a class file by using System.Configuration namespace
and using the ConfigurationManager class.

SqlConnection con =new SqlConnection(ConfigurationManager.ConnectionStrings["connectionStringName"].ConnectionString);