c# - 执行期间遇到 fatal error ...更新期间

Question

此代码放在按钮中。当我单击它更新数据时，会出现一个消息框错误，提示“命令执行期间遇到 fatal error ”。

您的回答会很有帮助。谢谢

 MySqlConnection connection = new MySqlConnection(MyConnectionString);
        MySqlCommand cmd;
        try
        {
            connection.Open();
            cmd = connection.CreateCommand();
            cmd.CommandText = "UPDATE student_offense SET TYPE=@TYPE,DATE_HAPPENED=@DH,DESCRIPTION=@DESC,SANCTION=@SANC" + 
                "Where STUDENT_NO = @STUDENT_NO And DESCRIPTION=@DESC And SANCTION=@SANC And DATE_HAPPENED=@DH";

            cmd.Parameters.AddWithValue("@TYPE", offense_combo.Text);
            cmd.Parameters.AddWithValue("@DH", date_hapen.Text);
            cmd.Parameters.AddWithValue("@DESC", description_txt.Text);
            cmd.Parameters.AddWithValue("@SANC", sanction_txt.Text);
            cmd.Parameters.AddWithValue("@STUDENT_NO", studentNo_txt.Text);
            cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            MessageBox.Show("updated");


            //refresh
            cmd.CommandText = "SELECT student_info.Student_no,student_info.Lastname,student_info.Firstname,student_offense.Type,student_offense.Description,student_offense.Date_Happened,student_offense.Sanction,student_offense.Date_Recorded from student_info,student_offense where student_info.student_no = student_offense.student_no";
            MySqlDataAdapter sda = new MySqlDataAdapter();
            sda.SelectCommand = cmd;
            dbdataset = new DataTable();
            sda.Fill(dbdataset);
            bSource = new BindingSource();

            bSource.DataSource = dbdataset;
            dataGridView1.DataSource = bSource;
            sda.Update(dbdataset);
            bSource.DataSource = dbdataset;
            dataGridView1.DataSource = bSource;

            student_no_valid.Visible = false;
            stud_no_error.Visible = true;

        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }

        listBox1.Items.Clear();
        description_txt.Text = "";
        studentNo_txt.Text = "";
        offense_combo.Text = "";
        current_date();
        sanction_txt.Text = "";

Answer 1

参数 @SANC 和 Where 之间缺少空格。

试试这个:

cmd.CommandText = "UPDATE student_offense SET TYPE=@TYPE,DATE_HAPPENED=@DH,
     DESCRIPTION=@DESC,SANCTION=@SANC" + " Where STUDENT_NO = @STUDENT_NO And 
                 DESCRIPTION=@DESC And SANCTION=@SANC And DATE_HAPPENED=@DH";

建议:如果您的DATE_HAPPENED 列类型是表中的Date，那么您需要发送正确的Date格式。

试试这个:假设用户以 dd-MM-yyyy 格式输入日期。

DateTime dt = DateTime.ParseExact(date_hapen.Text,"dd-MM-yyyy",
                                  CutureInfo.InvariantCulture);

现在在分配 DATE_HAPPENED 值时提供以下格式

cmd.Parameters.AddWithValue("@DH",dt.ToString("yyyy-MM-dd"));