Question

我正在从db中检索数据并显示在Label中。但是问题在于，这无法检索数据库表第一行数据。其打印第二行数据。如果我给了数据库第一行c_code，那么它给出了错误“位置2没有行”，请解决我的问题。谢谢

 private void Get_Purchasing_Amount()
        {
            try
            {
                string get_P_Amount = "";
                double var_P_Amount = 0;
                int var_C_Code = 0;
                string query = "select c_code as 'code' from `db_vegetable`.`tbl_payment_master`";
                DataTable dt_C_Code = method_Class.method_Class.FetchRecords(query);
                if (dt_C_Code.Rows.Count > 0)
                {
                    for (int i = 0; i <= dt_C_Code.Rows.Count; i++)
                    {
                        var_C_Code = Convert.ToInt32(dt_C_Code.Rows[i]["code"]);
                        if (var_C_Code.Equals(Convert.ToInt32(txt_Customer_Code.Text)))
                        {

                            if (check_All.Checked.Equals(true))
                            {
                                get_P_Amount = "SELECT IFNULL(`purchasing`,0) AS 'purchasing' FROM `db_vegetable`.`tbl_payment_master` WHERE `c_code` = " + txt_Customer_Code.Text + "";
                            }
                            else
                            {
                                string dt_Query = "select `id` as 'id' from `db_vegetable`.`tbl_order_details`";
                                DataTable dt_C_O = method_Class.method_Class.FetchRecords(dt_Query);
                                if (dt_C_O.Rows.Count > 0)
                                    get_P_Amount = "SELECT IFNULL(SUM(t_price),0) as 'purchasing' FROM `db_vegetable`.`tbl_order_details` WHERE `c_code` = " + txt_Customer_Code.Text + " AND (`date` BETWEEN '" + txt_From_Date.Text + "' AND '" + txt_To_Date.Text + "')";
                                else
                                    lbl_Purchasing_Amount.Text = "0";
                            }
                            DataTable dt = method_Class.method_Class.FetchRecords(get_P_Amount);
                            var_P_Amount = Convert.ToDouble(dt.Rows[0]["purchasing"]);
                            lbl_Purchasing_Amount.Text = var_P_Amount.ToString();

                        }
                        else
                        {
                            lbl_Purchasing_Amount.Text = "0";
                        }
                    }
                }
                else
                {
                    lbl_Purchasing_Amount.Text = "0";
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

Answer 1

我相信这可能是问题所在

for (int i = 0; i <= dt_C_Code.Rows.Count; ; i++) {...}

请考虑替换foreach (DataRow row in dt_C_Code.Rows) { ...}
如果重要的是逻辑上应该排在第一位，那么请考虑在您的SQL语句中使用order by子句。

Answer 2

现在的问题是解决问题是断关键字。

private void Get_Purchasing_Amount()
            {
                try
                {
                    string get_P_Amount = "";
                    double var_P_Amount = 0;
                    //int var_C_Code = 0;
                    string query = "select c_code as 'code' from `db_vegetable`.`tbl_payment_master`";
                    DataTable dt_C_Code = method_Class.method_Class.FetchRecords(query);
                    if (dt_C_Code.Rows.Count > 0)
                    {
                        for (int i = 0; i <= dt_C_Code.Rows.Count; i++)//these line generate error please check this
                        {

                            //var_C_Code = Convert.ToInt32(dt_C_Code.Rows[i]["code"]);
                            if (Convert.ToInt32(dt_C_Code.Rows[i]["code"]).Equals(Convert.ToInt32(txt_Customer_Code.Text)))
                            {
                                if (check_All.Checked.Equals(true))
                                {
                                    get_P_Amount = "SELECT IFNULL(`purchasing`,0) AS 'purchasing' FROM `db_vegetable`.`tbl_payment_master` WHERE `c_code` = " + txt_Customer_Code.Text + "";
                                }
                                else
                                {
                                    string dt_Query = "select `id` as 'id' from `db_vegetable`.`tbl_order_details`";
                                    DataTable dt_C_O = method_Class.method_Class.FetchRecords(dt_Query);
                                    if (dt_C_O.Rows.Count > 0)
                                        get_P_Amount = "SELECT IFNULL(SUM(t_price),0) as 'purchasing' FROM `db_vegetable`.`tbl_order_details` WHERE `c_code` = " + txt_Customer_Code.Text + " AND (`date` BETWEEN '" + txt_From_Date.Text + "' AND '" + txt_To_Date.Text + "')";
                                    else
                                        lbl_Purchasing_Amount.Text = "0";
                                }
                                DataTable dt = method_Class.method_Class.FetchRecords(get_P_Amount);
                                var_P_Amount = Convert.ToDouble(dt.Rows[0]["purchasing"]);
                                lbl_Purchasing_Amount.Text = var_P_Amount.ToString();
                                break;
                            }
                            else
                            {
                                lbl_Purchasing_Amount.Text = "0";
                            }
                        }
                    }
                    else
                    {
                        lbl_Purchasing_Amount.Text = "0";
                    }
                }
                catch (Exception)
                {

                }
            }

位置2 C＃运行时异常无行

2 个答案: