Why not "new SqlDataReader()" ?

[Ricola !]

Why do I say:

SqlDataReader dr;

instead of

SqlDataReader dr = new SqlDataReader();



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[Jon Skeet [C# MVP]]

Why do I say:

SqlDataReader dr;

instead of

SqlDataReader dr = new SqlDataReader();

There are no public constructors for SqlDataReader - if you could
construct one as above, what would you expect it to read?

You have to obtain a SqlDataReader reference from a call to a method of
another class - usually SqlCommand.ExecuteReader.

 

[Chris, Master of All Things Insignificant]

This is because your SqlCommand object is going to return to you an instance
of SqlDataReader. You never create a datareader object yourself.

if you did the following you would have two SqlDataReader objects in memory.
and the first one would no longer have a reference to it.
SqlDataReader dr = new SqlDataReader();
dr = SqlCommand.ExecuteReader();

dr is the following case is basically a pointer. The SqlCommand return the
object that dr points to.
SqlDataReader dr

hope that clears it up for you.
Chris

 

[Sahil Malik]

Well .. if you did do ..

SqlDataReader dr = new SqlDataReader();

What resultset will your data reader be working upon?

- Sahil Malik
http://codebetter.com/blogs/sahil.malik/