Executenonquery return value

问题

I want to perform a search on a table to see if record exists. I do not want to perform insert or update after. I have done this already but somehow I cannot get this to work. On my asp.net page I cannot seem to get any value returned. The error is "input string not in correct format" I ma sure it is obvious but I cannot seem to see it now!

here is my code:

Dim con As New SqlConnection("connstring")
Dim cmd As New SqlCommand("checkname", con)
cmd.CommandType = CommandType.StoredProcedure

cmd.Parameters.Add(New SqlParameter("@d", SqlDbType.Int))
cmd.Parameters("@id").Value = TextBox1.Text

Dim para As New SqlParameter
para.Direction = ParameterDirection.ReturnValue
para.ParameterName = "returnvalue"
cmd.Parameters.Add(para)

con.Open()


cmd.ExecuteNonQuery()
Dim exists As Integer
exists = Convert.ToInt32(cmd.Parameters("returnvalue").Value)
If exists = 1 Then
    Label1.Text = "You......"
         ElseIf exists = 0 Then
    Label1.Text = "You....."

End If
con.Close()

stored procedure:

CREATE PROCEDURE checkname 
    -- Add the parameters for the stored procedure here
    @id int
AS
  --This means it exists, return it to ASP and tell us
 -- SELECT 'already exists'

IF EXISTS(SELECT * FROM attendees WHERE id = @id)
BEGIN
RETURN 1
END
ELSE
BEGIN
   RETURN 0
END

回答1:

You need to ensure that you are passing an integer.

int intValue;
if(!int.TryParse(TextBox1.Text, out intValue))
{
     // Update your page to indicate an error

     return;

}

cmd.Parameters.Add(New SqlParameter("id", SqlDbType.Int));
cmd.Parameters("id").Value = intValue;

(Technically you don't need the "@" character when defining the parameters in the .NET code.)

回答2:

You have declared your procedure parameter as @d instead of @id. Also a return parameter cannot be an input parameter. The return value should be an exit code. You most likely want to create an output parameter and set that to 1 or zero inside of your stored procedure.

Edit: to clarify, the return value is generally regarded as an indicator of correct execution. Zero usually means success, where any other numeric value is generally regarded as an error code. That is why I recommended adding an output parameter instead of adding a return value parameter.

回答3:

ExecuteNonQuery returns the number of rows affected. Therefore the return values that you set in your stored procedure are thrown away and will not be returned by the ExecuteNonQuery method.

回答4:

ExecuteNonQuery is used to Insert / Delete / Update operations. Not for SELECT, you need either ExecuteScalar or ExecuteReader methods. This link will help you to know how to use output parameters : http://aspdotnet-suresh.blogspot.com/2010/10/introduction-here-i-will-explain-how-to.html

来源：https://stackoverflow.com/questions/5630002/executenonquery-return-value

标签

ASP.NET

return-value

executenonquery