C#中DataGridView错误列中的数据检索

Question

While retrieving the data from database it shows it in wrong grid view columns and even some are empty and also the data is shown in wrong columns.

I tried checking everything and didn't find any solution, I pasted some of my code here:

Note: I am using xampp database for testing purposes.

Here is a screen shot of the problem:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        gradeView3Intializer();

    }
    //ADD TO GDVIEW:
    private void populate3(string staffNo, string fName, string lName, string position, string sex, string dob, string salary, string branchNo)
    {
        dataGridView3.Rows.Add(staffNo, fName, lName, position, sex, dob, salary, branchNo);
    }

    //Retrive Function
    private void retrieve3()
    {
        dataGridView3.Rows.Clear();

        string sql = "SELECT * FROM staff;";
        cmd = new MySqlCommand(sql, con);

        try
        {
            con.Open();

            adapter = new MySqlDataAdapter(cmd);
            adapter.Fill(dt);

            //Loop through dt
            foreach (DataRow row in dt.Rows)
            {
                populate3(row[0].ToString(), row[1].ToString(), row[2].ToString(), row[3].ToString(), row[4].ToString(), row[5].ToString(), row[6].ToString(), row[7].ToString());
            }

            con.Close();

            //Clear DT
            dt.Rows.Clear();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Notice");
            con.Close();
        }
    }

    //Intializing GradView with Rows
    private void gradeView3Intializer()
    {
        dataGridView3.ColumnCount = 8;

        dataGridView3.Columns[0].Name = "Staff No";
        dataGridView3.Columns[1].Name = "First Name";
        dataGridView3.Columns[2].Name = "Last Name";
        dataGridView3.Columns[3].Name = "Position";
        dataGridView3.Columns[4].Name = "SEX";
        dataGridView3.Columns[5].Name = "DOB";
        dataGridView3.Columns[6].Name = "Salary";
        dataGridView3.Columns[7].Name = "Branch No";

        dataGridView3.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;

        // Selection Mode:

        dataGridView3.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
        dataGridView3.MultiSelect = false;
    }

    private void btnUpdate3_Click(object sender, EventArgs e)
    {
        try
        {
            string selected = dataGridView3.SelectedRows[0].Cells[0].Value.ToString();
            update3(selected, textBox8.Text, textBox7.Text, textBox6.Text, textBox5.Text, textBox25.Text, textBox26.Text, textBox27.Text, textBox28.Text);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Notice");
        }
    }

    private void btnRetrive3_Click(object sender, EventArgs e)
    {
        retrieve3();
    }


    private void dataGridView3_MouseClick(object sender, MouseEventArgs e)
    {
        try
        {
            textBox8.Text = dataGridView3.SelectedRows[0].Cells[0].Value.ToString();
            textBox7.Text = dataGridView3.SelectedRows[0].Cells[1].Value.ToString();
            textBox6.Text = dataGridView3.SelectedRows[0].Cells[2].Value.ToString();
            textBox5.Text = dataGridView3.SelectedRows[0].Cells[3].Value.ToString();

            textBox25.Text = dataGridView3.SelectedRows[0].Cells[4].Value.ToString();
            textBox26.Text = dataGridView3.SelectedRows[0].Cells[5].Value.ToString();
            textBox27.Text = dataGridView3.SelectedRows[0].Cells[6].Value.ToString();
            textBox28.Text = dataGridView3.SelectedRows[0].Cells[7].Value.ToString();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Notice");
        }
    }

Answer 1

Just a suggestion, in relation to:

string sql = "SELECT * FROM staff;";

Your code is relying on the the result fields being in the index positions you are expecting, but SELECT * will return data as per the database table structure, which may not match your expectation.

It is probably better to explicitly define the list of field names you want in your SQL statement. In the following example I can be confident in knowing exactly which positions my result fields are in, even if a column is moved in the underlying table structure.

string sql = "SELECT Field1, Field2, Field3 FROM staff;";

Answer 2

Finally after lots of struggles, I found a solution. I added:

dataGridView1.AutoGenerateColumns = true;
dataGridView2.AutoGenerateColumns = true; 
dataGridView3.AutoGenerateColumns = true;

to each retrieve() functions of my code and defined a new DataTable for each of the table in database, here is the code:

// NEW DataTables for each Table in Database
DataTable dt = new DataTable();
DataTable dt2 = new DataTable();
DataTable dt3 = new DataTable();

So this solved the problem for me :)