标量变量未声明

Question

protected void DropDownList8_SelectedIndexChanged(object sender, EventArgs e)
{
    var connectionString = (ConfigurationManager.ConnectionStrings["Connection"].ConnectionString);
    var updateCmd = "UPDATE [CarTab] SET Rent= 1 WHERE ([Model] = @Model)";
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(updateCmd, connection);
        command.Connection.Open();
        command.ExecuteNonQuery();
    }
}

Error : Must declare scalar variable for @Model. What should I remove/add there? Can't figure it out. Thanks in advance.

Answer 1

You can try with

 command.Parameters.AddWithValue("@Model", value);

You complete code

protected void DropDownList8_SelectedIndexChanged(object sender, EventArgs e)
{
    var connectionString = (ConfigurationManager.ConnectionStrings["Connection"].ConnectionString);
    var updateCmd = "UPDATE [CarTab] SET Rent= 1 WHERE ([Model] = @Model)";
    using (SqlConnection connection = new SqlConnection(
               connectionString))
    {
        using(var command = new SqlCommand(updateCmd, connection))
        {
          command.Parameters.AddWithValue("@Model", value); //Replace with your value

          command.Connection.Open();
          command.ExecuteNonQuery();
        }
    }
}

Answer 2

You must add the parameter @Model , like:

    updateCmd.Parameters.Add("@Model", SqlDbType.SomeType);
    updateCmd.Parameters["@Model"].Value = something;