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I'm trying to do an insertion to a Transaction table in SQL Server from a certain textboxes and one label on C# Windows Form, with the following code:

AppProcess abc = new AppProcess(); SqlConnection sqlconn1 = abc.GetConn(); SqlCommand sqlinsert = new SqlCommand("insert into Payment values (@TID,@EID,@CustID,@CFName,@CLName,@BID,@BName,@Price,@Qty,@TransDate)", sqlconn1); DataTable dtCustomer = new DataTable(); sqlconn1.Open(); sqlinsert.Parameters.Add(new SqlParameter("@TID", SqlDbType.VarChar, 10)); sqlinsert.Parameters.Add(new SqlParameter("@EID", SqlDbType.VarChar, 10)); sqlinsert.Parameters.Add(new SqlParameter("@CustID", SqlDbType.VarChar, 10)); sqlinsert.Parameters.Add(new SqlParameter("@CFName", SqlDbType.VarChar, 100)); sqlinsert.Parameters.Add(new SqlParameter("@CLName", SqlDbType.VarChar, 100)); sqlinsert.Parameters.Add(new SqlParameter("@BID", SqlDbType.VarChar, 10)); sqlinsert.Parameters.Add(new SqlParameter("@BName", SqlDbType.VarChar, 100)); sqlinsert.Parameters.Add(new SqlParameter("@Price", SqlDbType.Int)); sqlinsert.Parameters.Add(new SqlParameter("@Qty", SqlDbType.Int)); sqlinsert.Parameters.Add(new SqlParameter("@Transdate", SqlDbType.Date)); sqlinsert.Parameters["@TID"].Value = tidTxt.Text; sqlinsert.Parameters["@EID"].Value = eidTxt.Text; sqlinsert.Parameters["@CustID"].Value = cidTxt.Text; sqlinsert.Parameters["@CFName"].Value = cfnameTxt.Text; sqlinsert.Parameters["@CLName"].Value = clnameTxt.Text; sqlinsert.Parameters["@BID"].Value = bidTxt.Text; sqlinsert.Parameters["@BName"].Value = bnameTxt.Text; sqlinsert.Parameters["@Price"].Value = label17.Text; sqlinsert.Parameters["@Qty"].Value = qtychoiceTxt.Text; sqlinsert.Parameters["@Transdate"].Value = TransDateTxt.Text; sqlinsert.ExecuteNonQuery();

But when I run the app, it generates this error: click here to see what the error looks like

I'm confused which line triggers the error though. And how to convert the string to Int32?

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    what do you get from label17.Text and qtychoiceTxt.Text? From the exception detail, it is obvious your passing in strings instead of ints causing a FormatException.please check if those field values can be casted to int? Commented Oct 27, 2015 at 10:06
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    Also add validation to your forms so that users can't type arbitrary text in textboxes meant for numeric data Commented Oct 27, 2015 at 10:11
  • label17.Text is a total cost after the calculation of the quantity chosen on qtychoiceTxt.Text with the product price. I'm trying to save those values Commented Oct 27, 2015 at 10:11
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    Why are you using a label to show results? A label is there to label things. If you want to show the user a result, use a TextBox and set it to ReadOnly. Commented Oct 27, 2015 at 10:24

2 Answers 2

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Use should use like this code for convert:

command.Parameters.Add("@Qty", SqlDbType.Int).Value = Convert.ToInt32(qtychoiceTxt.Text);
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7 Comments

this could bereak if the value of any of the fields are not int. I suggest using TryParse instead.
@AmitKumarGhosh This is simple convert and not validation.for validation we should handle the value also we can use int.TryParse
@AmitKumarGhosh breaking is appropriate here. Better to ask the user to fix the data than store 0 by default. An accidental "payment" of 0 is not a happy situation
This question is about conversion and not about validation.For validation we have many solution.
@AmitKumarGhosh what is fine, is validators on the form, validation on the data-binding code (all this is available OOTB), and finally, yes, throw an exception and warn the user if previous validations fail. If my company payed me 0 Euros by accident, I would not be happy at all
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You have to Convert "label17.Text" and "qtychoiceTxt.Text" to integer by using Convert.ToInt32("string")

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3 Comments

this could bereak if the value of any of the fields are not int. Use TryParse instead
Not really - at this point it's better to throw an exception than record a payment of 0 quantity or 0 amount. TryParse should be used to validate the input befor the stored procedure is even called
we were just talking about the conversion not about the full functionality

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