How to execute a simple SQL query in C#

ExecuteSqlQuery.cs

using(SqlConnection conn = new SqlConnection(connString))
    using(SqlCommand command = new SqlCommand(query, conn))
        using (SqlDataAdapter dataAdapter = new SqlDataAdapter(command))
           dataAdapter.Fill(results);
           
using (SqlConnection conn = new SqlConnection(connString)) 
{
  conn.open();
  
  using (SqlCommand command = new SqlCommand(query, conn))
  {
    SqlDataReader reader = command.ExecuteReader();
    
    while (reader.read()) 
    {
      // Do Stuff
    }
  }
}