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 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.

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 = '[e-mail]';   connection.Open();   command.ExecuteNonQuery(); }