You can connect your C# application to data in a SQL Server database using the .NET Framework Data Provider for SQL Server. The first step in a C# application is to create an instance of the Server object and to establish its connection to an instance of Microsoft SQL Server.
The SqlConnection Object is Handling the part of physical communication between the C# application and the SQL Server Database. An instance of the SqlConnection class in C# has supported the Data Provider for SQL Server Database. The SqlConnection instance takes Connection String as argument and passes the value to the Constructor statement.