Re: help required in c# code
- From: sameer manohtra <sameermanohtra@xxxxxxxxx>
- To: programmingblind@xxxxxxxxxxxxx
- Date: Tue, 10 Aug 2010 11:37:39 +0530
hi mate,
actually, I have started working with ado.net very recently and I’m
not a much experienced programmer too.
Thanks for telling me the way, it worked.
The project I’m doing, I’ve got one more problem:
I have to use Microsoft access as database for this project. Since I
have been working with sql from whatever days I’ve learned ado.net, I
have hardly used access before this project.
Now when I’m trying to work with it, some of the things looking
puzzling to me and I’m not able to figure out a way to resolve them.
one recent is that I’m not able to store a double value which is not
a currency.
My user will be entering a value like 4.00 which I need to store in
the database.
I’m getting error while trying to store it with currency set as dataType.
In access, I did not find a dataType that represents decimal/double number.
Any idea how can I do it?
I’m learning a lot from this new project, but still I’m stuck up in a
lot of things before being able to complete the software that I am
developing.
Can you please help me doing this?
Sameer.
On 8/9/10, black ares <matematicianu2003@xxxxxxxxxxx> wrote:
> 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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