删除datagridview单元格点击事件

Question

删除 datagridview 单元格单击事件它表示信息已被删除，但在单击弹出消息后，即使我删除了某些信息，该信息仍然存在。请帮忙

 private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            string maincon = ConfigurationManager.ConnectionStrings["dbcs"].ConnectionString;
            SqlConnection sqlcon = new SqlConnection(maincon);
            int rfidno = Convert.ToInt32(dataGridView1.Rows[e.RowIndex].Cells["rfidno"].FormattedValue.ToString());

            try
            {
                SqlDataAdapter da = new SqlDataAdapter();
                sqlcon.Open();
                da.DeleteCommand = new SqlCommand("delete tbl_registerStudent where rfidno = '" + rfidno + "'", sqlcon);
                da.DeleteCommand.ExecuteNonQuery();

                MessageBox.Show("" + rfidno);
                MessageBox.Show("Delete Successfull");
                sqlcon.Close();
                bindGrid();
            }
            catch (SqlException ex)
            {
                MessageBox.Show(ex.Message);
            }

这是bindGrid的代码

public void bindGrid()
        {
            SqlConnection con = new SqlConnection(@"Data Source=DESKTOP-EB4EK81\SQLEXPRESS;Initial Catalog=TACLC;Integrated Security=True");
            SqlCommand cmd = new SqlCommand("Select * from tbl_registerStudent", con);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            dataGridView1.DataSource = dt;

        }
    ```

Answer 1

试试这个：

        try
        {
            SqlDataAdapter da = new SqlDataAdapter();
            sqlcon.Open();
            da.DeleteCommand = new SqlCommand("delete from tbl_registerStudent where rfidno = '" + rfidno + "'", sqlcon);
            da.DeleteCommand.ExecuteNonQuery();

            MessageBox.Show("" + rfidno);
            MessageBox.Show("Delete Successfull");
            sqlcon.Close();
            bindGrid();
        }
        catch (SqlException ex)
        {
            MessageBox.Show(ex.Message);
        }

Answer 2

一开始，你必须打开SqlConnection，然后执行你的命令，绑定结果，最后不要忘记关闭连接：

public void bindGrid()
{
   SqlConnection con = new SqlConnection(@"Data Source=DESKTOP-EB4EK81\SQLEXPRESS;Initial Catalog=TACLC;Integrated Security=True");
   con.Open()
   SqlCommand cmd = new SqlCommand("Select * from tbl_registerStudent", con);
   SqlDataAdapter sda = new SqlDataAdapter(cmd);
   DataTable dt = new DataTable();
   sda.Fill(dt);
   dataGridView1.DataSource = dt;
   con.Close();
}

为了不记得关闭SqlConnection，更好的方法是使用using 语句并让编译器为您生成此调用。

public void bindGrid()
{
   // This should be normally placed in a configuration file and read it from there. 
   string connectionString = @"Data Source=DESKTOP-EB4EK81\SQLEXPRESS;Initial Catalog=TACLC;Integrated Security=True";

   using(var sqlConnection = new SqlConnection(connectionString))
   {
       con.Open()
       SqlCommand cmd = new SqlCommand("Select * from tbl_registerStudent", con);
       SqlDataAdapter sda = new SqlDataAdapter(cmd);
       DataTable dt = new DataTable();
       sda.Fill(dt);
       dataGridView1.DataSource = dt;  
   }
}

此外，由于SqlCommand类继承自DbCommand，而后者实现了IDisposable接口，您应该记住，您应该再次使用using语句并使用要释放的资源。有关这方面的更多信息，请查看this。

话虽如此，建议的方法如下：

public void bindGrid()
{
   // This should be normally placed in a configuration file and read it from there. 
   string connectionString = @"Data Source=DESKTOP-EB4EK81\SQLEXPRESS;Initial Catalog=TACLC;Integrated Security=True";

   using(var sqlConnection = new SqlConnection(connectionString))
   {
       con.Open()
       using(var cmd = new SqlCommand("Select * from tbl_registerStudent", con))
       {
           SqlDataAdapter sda = new SqlDataAdapter(cmd);
           DataTable dt = new DataTable();
           sda.Fill(dt);
           dataGridView1.DataSource = dt;  
       }
    }
}