<Binary> in sql - c++

Question

I want to select all the binary data from a column of a SQL database (SQL Server Enterprise) using C++ query. I'm not sure what is in the binary data, and all it says is .
I tried this (it's been passed onto me to study off from) and I honestly don't 100% understand the code at some parts, as I commented):
SqlConnection^ cn = gcnew SqlConnection();
SqlCommand^ cmd;
SqlDataAdapter^ da;
DataTable^ dt;
cn->ConnectionString = "Server = localhost; Database=portable; User ID = glitch; Pwd = 1234";
cn->Open();
cmd=gcnew SqlCommand("SELECT BinaryColumn FROM RawData", cn);
da = gcnew SqlDataAdapter(cmd);
dt = gcnew DataTable("BinaryTemp"); //I'm confused about this piece of code, is it supposed to create a new table in the database or a temp one in the code?
da->Fill(dt);
for(int i = 0; i < dt->Rows->Count-1; i++)
{
String^ value_string;
value_string=dt->Rows[i]->ToString();
Console::WriteLine(value_string);
}
cn->Close();
Console::ReadLine();
but it only returns a lot of "System.Data.DataRow".
Can someone help me?
(I need to put it into a matrix form after I extract the binary data, so if anyone could provide help for that part as well, it'd be highly appreciated!)

Answer 1

dt->Rows[i] is indeed a DataRow ^. To extract a specific field from it, use its indexer:
array<char> ^blob=dt->Rows[i][0];
This extracts the first column (since you have only one) and returns an array representation of it.
To answer the question in your code, the way SqlDataAdapter works is like this:
you build a DataTable to hold the data to retrieve. You can fill in its columns, but you're not required to. Neither are you required to give it a name.
you build the adapter object, giving it a query and a connection object
you call the Fill method on the adapter, giving it the previously created DataTable to fill with whatever your query returns.
and you're done with the adapter. At this point you can dispose of it (for example inside a using statement if you're using C#).