sqldatareader error

Question

I want to check if the sqldatareader is null or not. So tried the following code:

if (x[k]!= DBNull.Value) 
{
 box.Text = Convert.ToString(x[k++]);
 if ((box.Text) != "")
 current[j - 1] = Convert.ToDouble(box.Text);
 else current[j - 1] = 0;
 box.Enabled = false;
}

However while trying to check the value within the datareader, it throws an error,"invalid attempt to read data when no data is present". How else should i check to see if data is there or not.!! please help. here x is an sqldatareader SqlDataReader x = cmd.ExecuteReader(); and cmd is a select commnand..

Answer 1

You can use SqlDataReader.HasRows - it is true if at least one row of data is present, alternatively you can read through all results using SqlDataReader.Read();

So for your example:

while(x.Read())
{
 //read stuff
}

Answer 2

You can do a null check and Has Row before accessing the DataRows.

like this

if(null != x && x.HasRows)
{
//Your code
}

• scooby: but still its showing the same error. !! although the if condition is satisfied, it is not able to execute the line box.Text = Convert.ToString(x[k++]); the fieldcount of x shows 6 but then why is it not able to read x[k] ? even when k = 0.
• Anuraj: Try Quickwatch the value of the x[k].
• scooby: is it possible to look into the value stored within the datareader? i mean, i dont think there is a way to peep into the value within x[0] or x[1]..
• Anuraj: Yes using Quick watch feature you can do this.