Connection of SQLServer from C#

ADO.NET is a set of common classes and interfaces used by every net program to interact with every kind of databases.

ADO.NET provides a set of built-in classes in the namespace System.Data.SqlClient to connect to a SqlServer database, also a set of classes (rather obsolete) for Oracle and a set of classes for generic OLEDB and ODBC driver each of them in their own namespace. The NET framework, installed on the client computer contains everything that is necessary to connect to SqlServer.

Other vendors have built specific ADO.NET providers using the same base classes and interfaces (MySql, the Oracle own ODP.NET provider, SQLite and so on...), of course you need to install these files downloading from the vendor site with any required software to connect to their databases.

The basic concepts of interaction with ADO.NET are:

1. Create an instance of a DbConnection passing a specific connection string (Examples of connectionstrings here at http://www.connectionstrings.com
2. Open the connection
3. Create specific instances of classes like DbCommand, DbDataReader or DbDataAdapter to execute commands to manipulate and retrieve your data. If necessary you could use other classes like DataTable and DataSet to store a disconnected copy of the data retrieved.
4. After that close and dispose the connection

And this is the basic picture. As you can see, a simple answer cannot cover this broad subject, so a bit of research is required.

Here a very simple example

string cmdText = "INSERT INTO Customers (Name, Address) VALUES (@name, @address)"
using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlCommand command = new SqlCommand(queryString, connection);
    command.Parameters.AddWithValue("@name", "Steve");
    command.Parameters.AddWithValue("@address", "Stackoverflow Street, 42");
    command.Connection.Open();
    command.ExecuteNonQuery();
}