c# - 检查数据库表Asp.net C#中的值是否

Question

我有一个存储过程，可以计算一个值在数据库中的次数。然而，在 for 循环后面的代码中，当它到达循环时会 (int)command.ExecuteScalar();停止并要求为 @invoice2 提供参数。

存储过程：

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

代码背后：

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

像这样的东西会更好，因为它会考虑两个参数。

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();
    }