How to learn ADO.NET

Question

I need to learn ADO.NET to build applications based on MS Office. I have read a good deal about ADO.NET in the MSDN Library, but everything seems rather messy to me.

What's the basics one must figure out when using ADO.NET? I think a few key words will suffice to let me organize my learning.

Answer 1

There are three key components (assuming ur using SQL server):

SQLConnection, SqlCommand, SqlDataReader

(if you're using something else, replace "Sql" with "Something", like "MySqlConnection", "OracleCommand"

Everything else is just built on top of that Example 1:

using (SqlConnection connection = new SqlConnection("CONNECTION STRING"))
using (SqlCommand command = new SqlCommand())
{
  command.commandText = "SELECT Name FROM Users WHERE Status = @OnlineStatus";
  command.Connection = connection;
  command.Parameters.Add("@OnlineStatus", SqlDbType.Int).Value = 1; //replace with enum
  connection.Open();
  using (SqlDataReader dr = command.ExecuteReader))
  {
      List<string> onlineUsers = new List<string>();
      while (dr.Read())
      {
         onlineUsers.Add(dr.GetString(0));
      }
  }
}

Example 2:

using (SqlConnection connection = new SqlConnection("CONNECTION STRING"))
using (SqlCommand command = new SqlCommand())
{
  command.commandText = "DELETE FROM Users where Email = @Email";
  command.Connection = connection;
  command.Parameters.Add("@Email", SqlDbType.VarChar, 100).Value = "[email protected]";
  connection.Open();
  command.ExecuteNonQuery();
}

Answer 2

Another way of gettinga command object is to call "connection.CreateCommand()". That way you shouldn't have to set the Commection property on the command object.