DataGridViewComboboxColumn-如何从数据库mySQL中的其他表添加和获取值

Question

另一个问题是关于显示和获取数据库mySQL中其他表的值。我添加了新的DataGridViewComboboxColumn，但是我无法从“ projekty”表中的值获取到“ modulate”表中的值。 “ projekty”表仅包含2列：ID type int和NAZWA_PROJEKTU type VARCHAR。有我的代码：

新tables.cs

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;

namespace KontrolaBazaDanych
{
    public partial class New_Tables : Form
    {
        public New_Tables()
        {
            InitializeComponent();
        }
        MySqlConnection connection;
        MySqlDataAdapter adapter, adapter2, adapter3, adapter4;
        DataSet ds, ds2, ds3, ds4;
        DataTable dt;
        public void New_Tables_Load(object sender, EventArgs e)
        {
            try
            {
                connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
                adapter = new MySqlDataAdapter("SELECT * FROM eltechnik_projekt1.pracownicy", connection);
                adapter2 = new MySqlDataAdapter("SELECT moduly.ID_MODULU, moduly.NAZWA, projekty.NAZWA_PROJEKTU FROM projekt1.moduly INNER JOIN projekt1.projekty ON projekty.ID = moduly.ID_PROJEKTU;", connection);
                adapter3 = new MySqlDataAdapter("SELECT zlecenia.ID_ZLECENIA, zlecenia.OPIS_ZLECENIA, zlecenia.NUMER_ZLECENIA, projekty.NAZWA_PROJEKTU FROM projekt1.zlecenia INNER JOIN projekt1.projekty ON projekty.ID = zlecenia.ID_PROJEKTU", connection);
                adapter4 = new MySqlDataAdapter("SELECT * FROM projekt1.projekty", connection);
                connection.Open();

                ds = new DataSet();
                adapter.Fill(ds, "pracownicy");
                dataGridView1.DataSource = ds.Tables["pracownicy"];

                ds2 = new DataSet();
                adapter2.Fill(ds2, "moduly");
                dataGridView2.DataSource = ds.Tables["moduly"];

                 ds3 = new DataSet();
                adapter3.Fill(ds3, "zlecenia");
                dataGridView3.DataSource = ds3.Tables["zlecenia"]; 

                ds4 = new DataSet();
                adapter4.Fill(ds4, "projekty");
                dataGridView4.DataSource = ds4.Tables["projekty"];

                dataGridView2.DataSource = loaddata();
                dataGridView1.Columns[0].Visible = false;
                dataGridView2.Columns[0].Visible = false;
                dataGridView3.Columns[0].Visible = false;
                dataGridView4.Columns[0].Visible = false;

                fillcombo();
                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                MySqlCommandBuilder cmbl = new MySqlCommandBuilder(adapter);
                adapter.Update(ds, "pracownicy");
                MySqlCommandBuilder cmbl2 = new MySqlCommandBuilder(adapter2);
                adapter2.Update(ds2, "moduly");
                MySqlCommandBuilder cmbl3 = new MySqlCommandBuilder(adapter3);
                adapter3.Update(ds3, "zlecenia");
                MySqlCommandBuilder cmbl4 = new MySqlCommandBuilder(adapter4);
                adapter4.Update(ds4, "projekty");
                MessageBox.Show("Informacja została zauktualizowana", "Aktualizacja", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

        private void dataGridView1_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView1.Rows[e.RowIndex].Cells[0].Value = e.RowIndex + 1;
        }

        private void dataGridView2_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView2.Rows[e.RowIndex].Cells[0].Value = e.RowIndex + 1;
        }

        private void dataGridView2_CurrentCellDirtyStateChanged(object sender, EventArgs e)
        {
            dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);
        }

        private void dataGridView3_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView3.Rows[e.RowIndex].Cells[0].Value = e.RowIndex + 1;
        }

        private void dataGridView4_RowEnter(object sender, DataGridViewCellEventArgs e)
        {
            dataGridView4.Rows[e.RowIndex].Cells[0].Value = e.RowIndex + 1;
        }

        private void button3_Click(object sender, EventArgs e)
        {
            MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
            DataTable dt = new DataTable();
            if (textBox1.Text.Length >= 0)
            {
                MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT * FROM projekt1.pracownicy WHERE IMIE LIKE '%" + textBox1.Text + "%' OR NAZWISKO LIKE '%" + textBox1.Text + "%';", connection);
                adapter.Fill(dt);
            }
            dataGridView1.DataSource = dt;
        }

        private void button4_Click(object sender, EventArgs e)
        {
            MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
            DataTable dt2 = new DataTable();
            if (textBox2.Text.Length >= 0)
            {
                MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT * FROM projekt1.moduly WHERE NAZWA LIKE '%" + textBox2.Text + "%' OR MODEL_MODULU LIKE '%" + textBox2.Text + "%';", connection);
                adapter.Fill(dt2);
            }
            dataGridView2.DataSource = dt2;
        }

        private void button5_Click(object sender, EventArgs e)
        {
            MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
            DataTable dt3 = new DataTable();
            if (textBox3.Text.Length >= 0)
            {
                MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT * FROM projekt1.zlecenia WHERE OPIS_ZLECENIA LIKE '%" + textBox3.Text + "%' OR NUMER_ZLECENIA LIKE '%" + textBox3.Text + "%';", connection);
                adapter.Fill(dt3);
            }
            dataGridView3.DataSource = dt3;
        }

        private void button6_Click(object sender, EventArgs e)
        {
            MySqlConnection connection = new MySqlConnection("datasource=localhost;port=3306;username=root;password=");
            DataTable dt4 = new DataTable();
            if (textBox4.Text.Length >= 0)
            {
                MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT * FROM projekt1.projekty WHERE NAZWA_PROJEKTU LIKE '%" + textBox4.Text + "%';", connection);
                adapter.Fill(dt4);
            }
            dataGridView4.DataSource = dt4;
        }

        private DataTable loaddata()
        {
            MySqlDataAdapter adapter = new MySqlDataAdapter();
            MySqlCommand cmd;
            DataSet ds = new DataSet();

            string sql = "SELECT * FROM projekt1.moduly";

            cmd = new MySqlCommand(sql, connection);

            adapter.SelectCommand = cmd;
            adapter.Fill(ds);

            dt = ds.Tables[0];

            return dt;
        }
        private void fillcombo()
        {
            DataGridViewComboBoxColumn combo = new DataGridViewComboBoxColumn();
            MySqlDataAdapter sda1 = new MySqlDataAdapter("SELECT * FROM projekt1.projekty", connection);
            combo.HeaderText = "NAZWA_PROJEKTU";
            combo.Name = "combo";
            ArrayList row = new ArrayList();

            foreach (DataRow dr in dt.Rows)
            {
                combo.DisplayMember = "NAZWA_PROJEKTU";
                combo.ValueMember = "ID";
                combo.DataSource = ds.Tables["projekty"];
            } 

            combo.Items.AddRange(row.ToArray());

            dataGridView2.Columns.Add(combo);
        }
    }
 }

有人可以解释如何解决吗？感谢您的帮助或建议。