If a DataReader holds one record at a time, then why...

Timothy

My understanding is that a DataReader can only hold one record in memory at any given time and has to keep the connection to the database open to read subsequent records in a forward only manner.

How is it then that I can bind a dataReader to a DataGrid and display multiple rows? I just don't get it.   I currently have this code:

            DbDataReader ddr = GetMetaClasses();
            GridView1.DataSource = ddr;
            GridView1.DataBind();

GetMetaClasses executes this stored procedure:

SELECT * FROM MetaClasses;

This is what my page displays:

ID	Name	FriendlyName	MetaClassType
1	NewsItems	News	Article
2	ClientPage	Client Page	Page

I don't understand how binding to the dataReader would work successfully and show all the results from the query if a dataReader can only hold one record in memory. Can someone please explain?? Thanks in advance!

2 Replies

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Niradhip Chakraborty17y ago
1) DataReader does not implement any specific interface so that it can
be bindable
2) DataReader is for reading data.So if some how u r able to bind
that,it won't allow u to edit that.So it's of no use.
3) DataReader is forward only,that means u can get a record at a time
but can't traverse back to the prev record.

This code shows how to bind gridview with data reader
Use this code on page load

void Page_Load(Object sender, EventArgs e)
{
String Q;
Sql command cmd;
Sql DataReader dr;

SqlConnection conn = new SqlConnection();

conn.ConnectionString = ConfigurationManager.ConnectionStrings        ["cn"].ConnectionString.ToString();

conn.Open();

Q = "select * from tablename";

cmd= New Sqlcommand(Q, conn);

dr = cmd.ExecuteReader();

Gridview1.DataSource = dr;

Gridview1.DataBind();
}
Kirtan Patel17y ago
When you bind Data reader to gridView

it iterates through records one by one and All records Rendered One bye one in HTML Table row

so as a result you see data in Grid View .