c# - 刷新数据 GridView 不起作用

Question

我想刷新数据 GridView ，但它不起作用 我有一个像这样的刷新方法:

public void Select() 
{
    SqlConnection con = new SqlConnection();
    SqlCommand cmd = new SqlCommand();
    SqlDataAdapter da = new SqlDataAdapter();
    DataTable dt = new DataTable();
    string cs = "server=(local);database=DB_Taxi;trusted_connection=yes;";
    con.ConnectionString = cs;
    con.Open();
    cmd.Connection = con;
    da.SelectCommand = cmd;
    cmd.CommandText = "SELECT * FROM Tbl_Driver";
    da.Fill(dt);
    con.Close();
    grid.DataSource = dt;
}

它在主窗体上。 我想以另一种名为 Add_Driver 的形式调用此函数。 为此，我在提交按钮中这样告诉它，因为我得到了相同的文本框值，并且在提交它们之后我想在数据库的数据 GridView 中显示它们。 我这样调用它:

private void btnOK_Click(object sender, EventArgs e)
    {
        if (txtID.Text != "" || txtName.Text != "" || txtLastName.Text != "" || txtMobile.Text != "" ||
            txtPhone.Text != "" || txtCar.Text != "" || txtGender.Text != "" || txtAddress.Text != "")
        {
            SqlConnection con = new SqlConnection();
            SqlCommand cmd = new SqlCommand();
            string cs = "server=(local);database=DB_Taxi;trusted_connection=yes;";
            con.ConnectionString = cs;
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "INSERT INTO Tbl_Driver(DriverID,DName,DLastName,DMobile,DAddress,DCar,DGender,DPhone) VALUES(@ID,@Name,@LastName,@Mobile,@Address,@Car,@Gender,@Phone)";
            cmd.Parameters.AddWithValue("@ID", txtID.Text);
            cmd.Parameters.AddWithValue("@Name", txtName.Text);
            cmd.Parameters.AddWithValue("@LastName", txtLastName.Text);
            cmd.Parameters.AddWithValue("@Mobile", txtMobile.Text);
            cmd.Parameters.AddWithValue("@Address", txtAddress.Text);
            cmd.Parameters.AddWithValue("@Car", txtCar.Text);
            cmd.Parameters.AddWithValue("@Gender", txtGender.Text);
            cmd.Parameters.AddWithValue("@Phone", txtPhone.Text);
            cmd.ExecuteNonQuery();
            con.Close();
            Empty();
            ////////////////////
            Main m = new Main();
            m.Select();
            ////////////////////
            MessageBox.Show("Added");
        }
        else
        {
            MessageBox.Show("Plese complete the form");                
        }            
    }

但数据 GridView 中的数据不会改变。 请帮忙! 但是当我在主窗体上调用这个方法时它起作用了 但我这样写主要方法:

Select()

Answer 1

试试这个。

public void Select() {
    SqlConnection con = new SqlConnection();
    SqlCommand cmd = new SqlCommand();
    SqlDataAdapter da = new SqlDataAdapter();
    DataTable dt = new DataTable();
    string cs = "server=(local);database=DB_Taxi;trusted_connection=yes;";
    con.ConnectionString = cs;
    con.Open();
    cmd.Connection = con;
    da.SelectCommand = cmd;
    cmd.CommandText = "SELECT * FROM Tbl_Driver";
    da.Fill(dt);
    con.Close();

    //clearing the datasource
    grid.DataSource = null;

    //set the datasource
    grid.DataSource = dt;
}