<p>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.</p>

<p>What are the basics one must figure out when using ADO.NET? I think a few key words will suffice to let me organize my learning.</p>

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 = "user@host.com";
  connection.Open();
  command.ExecuteNonQuery();
}
```
```