无法使用加法将类型“string”隐式转换为“int”[重复]

Question

如何修复错误？错误出现在 OrderNumber + AddOrderNumber 和 OrderNumber = sqlCmd1.ExecuteScalar().ToString();

谢谢这里是代码：

  int AddOrderNumber = 1;
        int OrderNumber;


        TextBox1.Text = OrderNumber + AddOrderNumber;
        TextBox2.Text = DateTime.Now.ToString("MM-dd-yyyy");
        TextBox3.Text = (string)Session["name"];


        using (SqlConnection con6 = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString))
        {

            //Grab Customer #
            using (SqlCommand sqlCmd1 = new SqlCommand { CommandText = "SELECT TOP 1 [OrderNumber] FROM [datarep].[dbo].[OrderHeader] Order By [OrderNumber] DESC", Connection = con6 })
            {
                con6.Open();
                object result = sqlCmd1.ExecuteScalar();

                if (result != null)
                {
                    OrderNumber = sqlCmd1.ExecuteScalar().ToString();

                }
                else
                {

                }
                con6.Close();
            }
        }

Answer 1

OrderNumber = sqlCmd1.ExecuteScalar().ToString();

OrderNumber 是int 类型，您正尝试将string 传递给该变量。在sqlCmd1.ExecuteScalar().ToString() 上执行Convert.ToInt32。

OrderNumber = Convert.ToInt32(sqlCmd1.ExecuteScalar().ToString());