Fill an array (or arraylist) from SqlDataReader

Question

Is there a way to fill an array via a SqlDataReader (or any other C# ADO.NET object) without looping through all the items? I have a query that is returning a single column

Answer 1

No, since SqlDataReader is a forward-only read-only stream of rows from a SQL Server database, the stream of rows will be looped through whether explicitly in your code or hidden in a framework implementation (such as DataTable's Load method).

It sounds like using a generic list and then returning the list as an array would be a good option. For example,

List<int> list = new List<int>();

using (SqlDataReader reader = cmd.ExecuteReader())
{
    while (reader.Read())
    {
         list.Add(reader.GetInt32(0));
    }    
}
return list.ToArray();

In response to your comment, calling ToArray() may be overhead, it depends. Do you need an array of objects to work with or would a generic collection (such as List<T> or ReadOnlyCollection<T>) be more useful?