Working With Datareader

akhilhp · April 9th, 2007, 04:41 AM

I am using datareaders to populate my gridview. the code is :
Datareader1 = sqlcmd.executereader

gridview1.datasource = datareader1
gridview1.databind()

Every thing is working fine. I only want following:
if the executereader returns no rows i.e query has generated no records, I wish too show the message "No Records Available" How to do that: I have tried to check by using :

if datareader1.read then
     gridview1.datasource = datareader1
     gridview1.databind()
else
     Show the message
endif
but here gridview1 gets one row less (because I think one row is lost in the read command and rest has been populated to gridview1)

Any Idea????

mike_remember · April 9th, 2007, 05:19 AM

Hi

Try this,

SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection) ;

            if (dr.HasRows)
            {
                grd.DataSource = dr;
                grd.DataBind();
            }
            else
            {
                lbl.Text = "No Records";
            }

Regards
Mike

Fortune favours the brave, so don't regret on missed oppurtunities.

akhilhp · April 10th, 2007, 12:18 AM

Thanks a lot..
It has worked...

Sjo · October 8th, 2007, 03:05 PM

Hi,

I am using IDataReader and trying to see if the query returns value or not. Since I am using IDataReader and that the only option I have for the getting the result using Microsoft.Enterprise.Library, is there any way I can check weather IDataReader has records or not?

dparsons · October 8th, 2007, 03:10 PM

Consider that your IDataReader instance is named dr, your code would be:

if(dr.HasRows)
{
//DataReader hasrows
}
else
{
//DataReader is empty
}

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Imar · October 8th, 2007, 03:18 PM

Quote:

quote:Consider that your IDataReader instance is named dr, your code would be:
if(dr.HasRows)

Unfortunately, that won't work, as IDataReader doesn't define a HasRows property.

You either need to cast your reader to something that does support HasRows or look a this work around: http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=356

Basically, it checks out the bound control afterwards to see if it contains aby rows....

Imar

---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004

dparsons · October 8th, 2007, 03:25 PM

Ahh silly me. Imar is quite right and his work around that he displays on his site will work. You could also make use of some logic and .Read() to determine if the IDataReader contains any data which is a similar approach to what Imar provides on his site.

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Imar · October 8th, 2007, 03:29 PM

Yeah, but just realize that, as akhilhp has pointed out, Read() "eats" a record....

Imar

---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004

dparsons · October 8th, 2007, 03:34 PM

True but logic like this:

Code:

bool hasRecords = false;

while(dr.Read())
{
 //do something if the IDataReader has data
 hasRecords = true;
}

if(!hasRecords){//do something else}

should aleviate the problem of data being lost. Obviously you can get this done with less lines as you show on your site, but this would still be a workable solution.

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Imar · October 8th, 2007, 03:40 PM

Yes, I see what you mean. That would work perfectly OK....

Imar

---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004