检查数据库表Asp.net C＃中的值

Question

I have a stored procedure that would count the number of times a value is in a database. However in the code behind for loop when it reaches (int)command.ExecuteScalar(); the loop stops and asks to supply parameter for @invoice2.

Stored Procedure:

select count(*) as CountInvoice where invoice1=@invoice1 or @invoice2=@invoice`2

Code Behind:

using (SqlCommand command = new SqlCommand("sp_Count", conn))
{

    foreach (TextBox textBox in placehldr1.Controls.OfType<TextBox>())
    {

        count += 1;

        command.CommandType = CommandType.StoredProcedure;
        string invoice = textBox.Text.TrimEnd();
        string parameter = string.Format("@invoice{0}", count);

        command.Parameters.AddWithValue(parameter, invoice);
        int invoiceCount = (int)command.ExecuteScalar();

        if (invoiceCount > 0)
        {

            lblError.Text = "Invoice number already exist";
            return;
        }
        command.Parameters.Clear();
    }

Answer 1

Would something like this work better as it factors in the two parameters.

select count(*) as CountInvoice where invoice1=@invoice1 or invoice2=@invoice2


using (SqlCommand command = new SqlCommand("sp_Count", conn))
{

    foreach (TextBox textBox in placehldr1.Controls.OfType<TextBox>())
    {

        count1 += 1;
        count2 += 1;
        command.CommandType = CommandType.StoredProcedure;
        string invoice = textBox.Text.TrimEnd();
        string parameter1 = string.Format("@invoice1", count1);
        string parameter2 = string.Format("@invoice2", count2);
        command.Parameters.AddWithValue(parameter, invoice);
        int invoiceCount = (int)command.ExecuteScalar();

        if (invoiceCount > 0)
        {

            lblError.Text = "Invoice number already exist";
            return;
        }
        command.Parameters.Clear();
    }