刪除datagridview單元格點擊事件

Question

刪除 datagridview 單元格單擊事件它說該信息已被刪除，但單擊彈出消息后，即使我刪除了該特定信息，該信息仍然存在。 請幫忙

 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);
            }

這是bindGrid的代碼

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

嘗試這個：

        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

最初，您必須打開 SqlConnection，然后執行您的命令，綁定結果，最后不要忘記關閉連接：

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();
}

為了您不記得關閉SqlConnection ，更好的方法是使用using語句並讓編譯器為您生成此調用。

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，由於SqlCommand類繼承自DbCommand ，后者實現了IDisposable接口，因此您應該記住，您應該再次using語句並釋放已用資源。 有關這方面的更多信息，請查看此。

話雖如此，建議的方法如下：

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;  
       }
    }
}