Re: help required in c# code
- From: "black ares" <matematicianu2003@xxxxxxxxxxx>
- To: <programmingblind@xxxxxxxxxxxxx>
- Date: Mon, 9 Aug 2010 14:46:39 +0300
Hello, you miss understood the use of the datareader.
The data reader is a class which help you to read results from a query row
by row.
So it is what we call connected way to use with databases.
After the line with executereader,
you must do
dr.read();
then dr.get(x) or dr.get ("columnName");
for your help, when you want to get only a number,
so when you know that the query you use will return only a value, so a table
formed from a row and a column,
you can use better executeScalar instead of others.
Execute scalar retyurns an object you can cast using regular casting
algoritm so you can do:
int val=(int)cmd.executescalar(...);
----- Original Message -----
From: "sameer manohtra" <sameermanohtra@xxxxxxxxx>
To: "programmingblind" <programmingblind@xxxxxxxxxxxxx>
Sent: Monday, August 09, 2010 1:47 PM
Subject: help required in c# code
Hi mates,
I am doing a project in c# with ado.net and I got stuck at a place.
At one place in the code, i’m reading a column of table of my database
and want to store it in a local variable.
Basically, the table has a number, which I will use further for some
addition/subtraction operation.
The problem is, that I’m not able to convert the output of the
dataReader into integer.
It gives the following exception:
---
System.InvalidCastException was unhandled
Message="Unable to cast object of type
'System.Data.OleDb.OleDbDataReader' to type 'System.IConvertible'."
---
my code is this:
---
con.Open();
OleDbCommand cmd = new OleDbCommand("select
lastBalance from Textile");
cmd.Connection = con;
OleDbDataReader dr= cmd.ExecuteReader();
dr.Close();
con.Close();
int balance =
Convert.ToInt32(dr);
---
I have tried all that I knew, but could not find a solution.
Can you help?
Please, tell me how can I convert the output of dataReader to an integer
value.
The help will be appreciated.
sameer
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