How to read three columns of a SQL Server table with SqlDataReader and store values in double[, ,] array

Question

I have a table in SQL Server that stores x, y, z values as floats, I would like to get the values and store them in a tridimensional array.

I have been searching and I have seen people would go for adding values to a list, as we do not know how many items we could get, like:

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

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

However I do not know if it is possible to read table and get and store elements at once

I was trying to get three lists like this:

List<double> xValuesList = (from IDataRecord r in dataReader
                     select (double)r["xVal"]
                    ).ToList();

List<double> yValuesList = (from IDataRecord r in dataReader
                     select (double)r["yVal"]
                    ).ToList();
List<double> zValuesList = (from IDataRecord r in dataReader
                     select (double)r["zVal"]
                    ).ToList();

and then loop and get a tridimensional array from all these 3 lists..

But I think using a struct or something would be better, but I do not know how to do it.

Are you sure that you need a tridimensional array and not a tuple with three elements? — Tomas Pastircak
– Tomas Pastircak, Commented Apr 12, 2014 at 23:32

Dmitry · Accepted Answer · 2014-04-12 23:42:05Z

2

If I understood your question correctly, try to create a class like this:

public class Point3D
{
    public readonly double X;
    public readonly double Y;
    public readonly double Z;

    public Point3D(double x, double y, double z)
    {
        X = x;
        Y = y;
        Z = z;
    }
}

And read a data from the table directly into the list of instances of this class as follows:

List<Point3D> list = new List<Point3D>();

using (SqlDataReader reader = cmd.ExecuteReader())
{
    while (reader.Read())
    {
        list.Add(new Point3D(reader.GetDouble(0), reader.GetDouble(1), reader.GetDouble(2)));
    }    
}

edited Apr 12, 2014 at 23:42

answered Apr 12, 2014 at 23:35

Dmitry

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3 Comments

edgarmtze Over a year ago

If I already have a struct called Point but has other attributes How can I change the code to work?

public struct Point : IEquatable<Point>, IComparable<Point>     {         public double _X;         public double _Y;         public double _Z; //  getters setters and constructors...

edgarmtze Over a year ago

so if the select statement is string lcQuery = "SELECT X, Y,Z FROM cmYTAB WHERE inId = '" + id + "'"; I would get values by reader.GetDouble(0), reader.GetDouble(1), reader.GetDouble(2) right?

Dmitry Over a year ago

Yup, right! And also you should pass these values to the constructor of the Point class.

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