c# - 如何将带有日期时间的列中的每个单元格从 ms excel 插入到 mysql 数据库？

Question

我用 C# .net 编程了大约 1 个月。现在我正在尝试用这种语言编写代码，将数据从 MS excel (Office 365) 导入到 datagridview，然后导入到 mysql 数据库。在这种情况下，我有一个表，我在表中执行此操作:

Order_status table from MS Excel to DataGridView

当我将数据导入到 datagridview 时，我尝试将数据插入到 mysql 数据库中。所有代码如下:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using System.Collections;
using System.Data.OleDb;
using System.IO;
using System.Configuration;

namespace ControlDataBase
{
    public partial class New_Tables : Form
    {
        public New_Tables()
        {
            InitializeComponent();
        }
        Form1 frm1 = (Form1)Application.OpenForms["Form1"];

        private void btnClose_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void ImportData_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog ofd = new OpenFileDialog() { Filter = "Excel Files|*.xlsx;*.xlsm;*.xlsb;*.xltx;*.xltm;*.xls;*.xlt;*.xls;*.xml;*.xml;*.xlam;*.xla;*.xlw;*.xlr;", ValidateNames = true })
            {
                if (ofd.ShowDialog() == DialogResult.OK)
                {
                    FileInfo fi = new FileInfo(ofd.FileName);
                    string FileName1 = ofd.FileName;

                    string excel = fi.FullName;

                    if (ofd.FileName.EndsWith(".xlsx"))
                    {
                        StrConn = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + excel + ";Extended Properties=\"Excel 12.0;\"";
                    }

                    if (ofd.FileName.EndsWith(".xls"))
                    {
                        StrConn = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + excel + ";Extended Properties=\"Excel 1.0;HDR=Yes;IMEX=1\"";
                    }
                    OleDbConnection oledbconn = new OleDbConnection(StrConn);

                    OleDbDataAdapter dta5 = new OleDbDataAdapter("SELECT * FROM [Order_status$]", oledbconn);
                    oledbconn.Open();

                    DataSet dsole5 = new DataSet();
                    dta5.Fill(dsole5, "Order_status$");
                    datagrdStatus_order.DataSource = dsole5.Tables["Order_status$"];

                    oledbconn.Close();

                    MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
                    connection.Open();

                    for (int i = 0; i < datagrdStatus_order.Rows.Count; i++)
                    {
                        MySqlCommand cmd = new MySqlCommand("INSERT IGNORE INTO try1.order_status(ID_WORKER, ID_ORDER, ID_MODULE, ID_PROJECT, AMOUNT_OF_PRODUCTS, BEGIN_DATE, END_DATE) SELECT workers.ID_WORKER, orders.ID_ORDER, module.ID_MODULE, projects.ID, @AMOUNT_OF_PRODUCTS, @BEGIN_DATE, @END_DATE FROM try1.workers INNER JOIN try1.orders INNER JOIN try1.modules INNER JOIN try1.projects WHERE workers.FNAME = @FNAME AND workers.LNAME = @LNAME AND workers.ID_WORKER = @ID_WORKER AND orders.ORDER_DESC = @ORDER_DESC AND orders.ORDER_NUMBER = @ORDER_NUMBER AND modules.NAME = @MODULES_NAME AND projects.PROJECT_NAME = @PROJECT_NAME", connection);

                    DateTime begin_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[8].Value);
                    DateTime end_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[9].Value);

                        cmd.Parameters.AddWithValue("@ID_WORKER", datagrdStatus_order.Rows[i].Cells[0].Value);
                        cmd.Parameters.AddWithValue("@FNAME", datagrdStatus_order.Rows[i].Cells[1].Value);
                        cmd.Parameters.AddWithValue("@LNAME", datagrdStatus_order.Rows[i].Cells[2].Value);
                        cmd.Parameters.AddWithValue("@ORDER_DESC", datagrdStatus_order.Rows[i].Cells[3].Value);
                        cmd.Parameters.AddWithValue("@NUMBER_ORDER", datagrdStatus_order.Rows[i].Cells[4].Value);
                        cmd.Parameters.AddWithValue("@MODULES_NAME", datagrdStatus_order.Rows[i].Cells[5].Value);
                        cmd.Parameters.AddWithValue("@PROJECT_NAME", datagrdStatus_order.Rows[i].Cells[6].Value);
                        cmd.Parameters.AddWithValue("@AMOUNT_OF_PRODUCTS", datagrdStatus_order.Rows[i].Cells[7].Value);
                        cmd.Parameters.AddWithValue("@BEGIN_DATE", begin_date);
                        cmd.Parameters.AddWithValue("@END_DATE", end_date);
                        cmd.ExecuteNonQuery();
                    }
                    connection.Close();
                    MessageBox.Show("The data are imported correctly");

                    loaddataalldatagridview();
                }
            }
        }

        private void loaddataalldatagridview()
        {
            frm1.loaddata5();
        }
    }
}

当我执行该代码时，我在代码行收到错误:

DateTime begin_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[8].Value);

显示:

System.InvalidCastException: "You cannot cast from the DBNull element to other types."

但它插入了大部分导入的数据，但不是全部。我想导入所有数据。

我尝试过什么？

1) 我只是添加到日期时间对象 .ToString();

            for (int i = 0; i < datagrdStatus_order.Rows.Count; i++)
            {
                MySqlCommand cmd = new MySqlCommand("INSERT IGNORE INTO try1.order_status(ID_WORKER, ID_ORDER, ID_MODULE, ID_PROJECT, AMOUNT_OF_PRODUCTS, BEGIN_DATE, END_DATE) SELECT workers.ID_WORKER, orders.ID_ORDER, module.ID_MODULE, projects.ID, @AMOUNT_OF_PRODUCTS, @BEGIN_DATE, @END_DATE FROM try1.workers INNER JOIN try1.orders INNER JOIN try1.modules INNER JOIN try1.projects WHERE workers.FNAME = @FNAME AND workers.LNAME = @LNAME AND workers.ID_WORKER = @ID_WORKER AND orders.ORDER_DESC = @ORDER_DESC AND orders.ORDER_NUMBER = @ORDER_NUMBER AND modules.NAME = @MODULES_NAME AND projects.PROJECT_NAME = @PROJECT_NAME", connection);

                DateTime begin_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[8].Value.ToString());
                DateTime end_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[9].Value.ToString());

                cmd.Parameters.AddWithValue("@ID_WORKER", datagrdStatus_order.Rows[i].Cells[0].Value);
                cmd.Parameters.AddWithValue("@FNAME", datagrdStatus_order.Rows[i].Cells[1].Value);
                cmd.Parameters.AddWithValue("@LNAME", datagrdStatus_order.Rows[i].Cells[2].Value);
                cmd.Parameters.AddWithValue("@ORDER_DESC", datagrdStatus_order.Rows[i].Cells[3].Value);
                cmd.Parameters.AddWithValue("@NUMBER_ORDER", datagrdStatus_order.Rows[i].Cells[4].Value);
                cmd.Parameters.AddWithValue("@MODULES_NAME", datagrdStatus_order.Rows[i].Cells[5].Value);
                cmd.Parameters.AddWithValue("@PROJECT_NAME", datagrdStatus_order.Rows[i].Cells[6].Value);
                cmd.Parameters.AddWithValue("@AMOUNT_OF_PRODUCTS", datagrdStatus_order.Rows[i].Cells[7].Value);
                cmd.Parameters.AddWithValue("@BEGIN_DATE", begin_date);
                cmd.Parameters.AddWithValue("@END_DATE", end_date);
                cmd.ExecuteNonQuery();
            }

但它表明:

System.FormatException: "The string was not recognized as a valid DateTime."

2)我尝试通过向对象添加字符串然后转换为日期时间:

            for (int i = 0; i < datagrdStatus_order.Rows.Count; i++)
            {
                MySqlCommand cmd = new MySqlCommand("INSERT IGNORE INTO try1.order_status(ID_WORKER, ID_ORDER, ID_MODULE, ID_PROJECT, AMOUNT_OF_PRODUCTS, BEGIN_DATE, END_DATE) SELECT workers.ID_WORKER, orders.ID_ORDER, module.ID_MODULE, projects.ID, @AMOUNT_OF_PRODUCTS, @BEGIN_DATE, @END_DATE FROM try1.workers INNER JOIN try1.orders INNER JOIN try1.modules INNER JOIN try1.projects WHERE workers.FNAME = @FNAME AND workers.LNAME = @LNAME AND workers.ID_WORKER = @ID_WORKER AND orders.ORDER_DESC = @ORDER_DESC AND orders.ORDER_NUMBER = @ORDER_NUMBER AND modules.NAME = @MODULES_NAME AND projects.PROJECT_NAME = @PROJECT_NAME", connection);

                DateTime begin_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[8].Value);
                string MysqlFormatDate = begin_date.ToString("yyyy-MM-dd HH:mm:ss");
                DateTime begin_date2 = Convert.ToDateTime(MysqlFormatDate);

                DateTime end_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[9].Value);
                string MysqlFormatDate2 = end_date.ToString("yyyy-MM-dd HH:mm:ss");
                DateTime end_date2 = Convert.ToDateTime(MysqlFormatDate2);

                cmd.Parameters.AddWithValue("@ID_WORKER", datagrdStatus_order.Rows[i].Cells[0].Value);
                cmd.Parameters.AddWithValue("@FNAME", datagrdStatus_order.Rows[i].Cells[1].Value);
                cmd.Parameters.AddWithValue("@LNAME", datagrdStatus_order.Rows[i].Cells[2].Value);
                cmd.Parameters.AddWithValue("@ORDER_DESC", datagrdStatus_order.Rows[i].Cells[3].Value);
                cmd.Parameters.AddWithValue("@NUMBER_ORDER", datagrdStatus_order.Rows[i].Cells[4].Value);
                cmd.Parameters.AddWithValue("@MODULES_NAME", datagrdStatus_order.Rows[i].Cells[5].Value);
                cmd.Parameters.AddWithValue("@PROJECT_NAME", datagrdStatus_order.Rows[i].Cells[6].Value);
                cmd.Parameters.AddWithValue("@AMOUNT_OF_PRODUCTS", datagrdStatus_order.Rows[i].Cells[7].Value);
                cmd.Parameters.AddWithValue("@BEGIN_DATE", begin_date2);
                cmd.Parameters.AddWithValue("@END_DATE", end_date2);
                cmd.ExecuteNonQuery();
            }

但它也不起作用(它显示了像第一次尝试一样的错误)。

3)我声明了字符串对象并转换为日期时间:

            for (int i = 0; i < datagrdStatus_order.Rows.Count; i++)
            {
                MySqlCommand cmd = new MySqlCommand("INSERT IGNORE INTO try1.order_status(ID_WORKER, ID_ORDER, ID_MODULE, ID_PROJECT, AMOUNT_OF_PRODUCTS, BEGIN_DATE, END_DATE) SELECT workers.ID_WORKER, orders.ID_ORDER, module.ID_MODULE, projects.ID, @AMOUNT_OF_PRODUCTS, @BEGIN_DATE, @END_DATE FROM try1.workers INNER JOIN try1.orders INNER JOIN try1.modules INNER JOIN try1.projects WHERE workers.FNAME = @FNAME AND workers.LNAME = @LNAME AND workers.ID_WORKER = @ID_WORKER AND orders.ORDER_DESC = @ORDER_DESC AND orders.ORDER_NUMBER = @ORDER_NUMBER AND modules.NAME = @MODULES_NAME AND projects.PROJECT_NAME = @PROJECT_NAME", connection);

                string begin_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[8].Value).ToString("yyyy-MM-dd HH:mm:ss");
                string end_date = Convert.ToDateTime(datagrdStatus_order.Rows[i].Cells[9].Value).ToString("yyyy-MM-dd HH:mm:ss");

                cmd.Parameters.AddWithValue("@ID_WORKER", datagrdStatus_order.Rows[i].Cells[0].Value);
                cmd.Parameters.AddWithValue("@FNAME", datagrdStatus_order.Rows[i].Cells[1].Value);
                cmd.Parameters.AddWithValue("@LNAME", datagrdStatus_order.Rows[i].Cells[2].Value);
                cmd.Parameters.AddWithValue("@ORDER_DESC", datagrdStatus_order.Rows[i].Cells[3].Value);
                cmd.Parameters.AddWithValue("@NUMBER_ORDER", datagrdStatus_order.Rows[i].Cells[4].Value);
                cmd.Parameters.AddWithValue("@MODULES_NAME", datagrdStatus_order.Rows[i].Cells[5].Value);
                cmd.Parameters.AddWithValue("@PROJECT_NAME", datagrdStatus_order.Rows[i].Cells[6].Value);
                cmd.Parameters.AddWithValue("@AMOUNT_OF_PRODUCTS", datagrdStatus_order.Rows[i].Cells[7].Value);
                cmd.Parameters.AddWithValue("@BEGIN_DATE", begin_date);
                cmd.Parameters.AddWithValue("@END_DATE", end_date);
                cmd.ExecuteNonQuery();
            }

但随后它显示错误:

System.InvalidCastException: "You cannot cast from the DBNull element to other types."

我不知道如何解决这个问题。我正在寻找解决方案，但没有找到？有人可以解释一下如何解决吗？有任何想法吗？感谢您的任何帮助和建议。 :)

Answer 1

为了使用 Excel 操作，首先要做的就是将 Microsoft.Office 对象库引用包含到项目中。

使用 Excel=Microsoft.Office.Interop.Excel;

并尝试像这样转换日期时间:

DateTime begin_Date= DateTime.ParseExact(row[8].ToString(), "yyyy-MM-dd", cultureUS, DateTimeStyles.None);