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Error in reading DataReader

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Join Date: Aug 2008

Posts: 96

Reputation: Tank50 is an unknown quantity at this point

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Tank50

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Junior Poster in Training

Error in reading DataReader

Jul 23rd, 2009

Hi

I want to read the content in datareader.So I use below coding to do that
if (dataReader4.IsDBNull(0)){

}
but I run above coding it gave me an error meassage.The error Meassage is
"Invalid attempt to read when no data is present".

then I use below coding
dataReader4["Email"]==null
but It also gave me above error meassage.There is no record for that field,that only for one record,for othere records there are email address.

Thanks
Tank50

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Join Date: Oct 2008

Posts: 2,668

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adatapost

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Posting Maven

Re: Error in reading DataReader

Jul 23rd, 2009

You missed Read() method.

 Help with Code Tags 
 c# Syntax (Toggle Plain Text) 
if (dataReader4.Read())
   var=dataReader4.IsDBNull(0);
}
if (dataReader4.Read())
   var=dataReader4.IsDBNull(0);
}

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Join Date: Jan 2008

Posts: 483

Reputation: DangerDev has a spectacular aura about

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DangerDev

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Re: Error in reading DataReader

Jul 23rd, 2009

Hi,
Read example here. It will help you. You have to call dataReader4.Read() before reading it. If still problem persist please post code what you have done so far.

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Join Date: Jul 2008

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Reputation: maestridaniele is an unknown quantity at this point

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maestridaniele maestridaniele is offline

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Newbie Poster

Re: Error in reading DataReader

Jul 23rd, 2009

•

Originally Posted by Tank50

Hi

I want to read the content in datareader.So I use below coding to do that
if (dataReader4.IsDBNull(0)){

}
but I run above coding it gave me an error meassage.The error Meassage is
"Invalid attempt to read when no data is present".

then I use below coding
dataReader4["Email"]==null
but It also gave me above error meassage.There is no record for that field,that only for one record,for othere records there are email address.

Thanks
Tank50

//****************************************************
Hi,
try this code to read datareader...

// Instance a new object
Object a = new Object();

// Check if datareader is null
if (datareader == null)
return;

// Get data from datareader
while (datareader.Read())
{
// Code example...
a = datareader.GetValue(0);
}

Hope it works for you...

See ya!!!

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Join Date: Mar 2008

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Reputation: djjaries is an unknown quantity at this point

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djjaries

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Newbie Poster

Re: Error in reading DataReader

Jul 23rd, 2009

It looks like you start using the reader without reading some data first.

 Help with Code Tags 
 c# Syntax (Toggle Plain Text) 
void ReadData(SqlConnection conn, string sql)
SqlDataReader datareader;
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = sql;
datareader = cmd.ExecuteReader();
while (datareader.Read()) {
 // perform your code here
}
}
void ReadData(SqlConnection conn, string sql)
SqlDataReader datareader;
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = sql;
datareader = cmd.ExecuteReader();
while (datareader.Read()) {
 // perform your code here
}
}