Question

到目前为止，我已设法从按钮单击事件的datagrid视图中删除记录，但问题是数据库没有更改。

我使用datagrid_booktitles.Rows.RemoveAt(oneCell.RowIndex);从数据网格中删除了行，cmd = new MySqlCommand("DELETE FROM sarasavi_library . book_title WHERE book_number = 'book_number';");将其从数据库。

以下是删除按钮点击事件的完整代码：

private void btn_delete_Click(object sender, EventArgs e)
    {
        foreach (DataGridViewCell oneCell in datagrid_booktitles.SelectedCells)
        {
            if (oneCell.Selected)
                datagrid_booktitles.Rows.RemoveAt(oneCell.RowIndex);

            cmd = new MySqlCommand("DELETE FROM `sarasavi_library`.`book_title` WHERE `book_number`= 'book_number';");
        }
    }

我在这里做错了吗？我觉得我的MySQL命令存在问题，但我无法想到另一种方式。有什么想法吗？

Answer 1

您需要创建并提供MySqlConnection实例，以便在数据库上执行命令。

private void btn_delete_Click(object sender, EventArgs e)
{
    foreach (DataGridViewCell oneCell in datagrid_booktitles.SelectedCells)
    {
        if (oneCell.Selected == false) continue;

        datagrid_booktitles.Rows.RemoveAt(oneCell.RowIndex);
        string query = 
            "DELETE FROM `sarasavi_library`.`book_title` WHERE `book_number`='book_number'"

        using(var conn = new MySqlConnection("yourConnectionString"))
        {
            using(var command = new MySqlCommand(query, conn))
            {
                conn.Open();
                command.ExecuteNonQuery();
            }
        }
    }
}

Answer 2

尝试使用此方法从数据库中删除所选的datagridview行。

SqlConnection con=new SqlConnection(@"Data Source=.\SqlExpress;Initial      Catalog=DatabaseName;Integrated Security=True"); 

 SqlCommand cmd = new SqlCommand();

if (dataGridView1.Rows.Count > 1 && dataGridView1.SelectedRows[0].Index != dataGridView1.Rows.Count - 1)

 {

 delcmd.CommandText = "DELETE FROM table_Name WHERE Column_Name=" + dataGridView1.SelectedRows[0].Cells[0].Value.ToString() + "";

                con.Open();

                delcmd.Connection = con;

                delcmd.ExecuteNonQuery();

                con.Close();
                dataGridView1.Rows.RemoveAt(dataGridView1.SelectedRows[0].Index);

                MessageBox.Show("Row has been Deleted");


            }

Answer 3

想想我找到了答案。我已将datagrid值分配给字符串并在数据库查询中使用它。

foreach (DataGridViewCell oneCell in datagrid_booktitles.SelectedCells)
{
   if (oneCell.Selected == false) continue;

   string i = datagrid_booktitles.SelectedRows[0].Cells[1].Value.ToString();
   datagrid_booktitles.Rows.RemoveAt(oneCell.RowIndex);
   string query = "DELETE FROM `sarasavi_library`.`book_title` WHERE `book_number`='" + i +"'";

   using (var conn = new MySqlConnection(ConfigurationManager.ConnectionStrings["Constring"].ToString()))
   {
      using (var cmd = new MySqlCommand(query, conn))
      {
         conn.Open();
         cmd.ExecuteNonQuery();
      }
    }
  }

如何删除数据网格视图中的行并在删除按钮单击事件上更新MySQL数据库？

3 个答案: