如何从mysql数据库显示数据int文本框，并在进行少量更改后再次更新？

Question

我有一个供学生使用的表，单击搜索按钮后，我已成功检索数据并将其显示在文本框中，然后将几个单词更改为某些文本框，然后单击了另一个按钮以更新查询但是，当我检查数据库时，没有进行任何更改，非常感谢您的帮助，我是C＃和Visual Studio的新手。

这是我的表单代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace UA_SMS_Grade_Inquiry_System
{
    public partial class UpdateStudent : Form
    {
        public UpdateStudent()
        {
            InitializeComponent();
        }

        private void searchStudButton_Click(object sender, EventArgs e)
        {
                string search = this.searchStudTbox.Text;
                MySqlConnectionStringBuilder connBuilder = new MySqlConnectionStringBuilder();

                connBuilder.Add("Database", "grade_inquiry");
                connBuilder.Add("Data Source", "localhost");
                connBuilder.Add("User Id", "root");
                connBuilder.Add("Password", "");

                MySqlConnection connection = new MySqlConnection(connBuilder.ConnectionString);
                connection.Open();
                try
                {
                    MySqlCommand cmd = new MySqlCommand("SELECT * FROM students INNER JOIN courses ON students.course = courses.course INNER JOIN departments ON departments.department = courses.department WHERE student_school_id ='" + search + "'", connection);
                    MySqlDataReader reader = cmd.ExecuteReader();
                    if (reader.HasRows)
                    {
                        while (reader.Read())
                        {
                            this.updateStudIdTbox.Text = (reader["student_school_id"].ToString());
                            this.updateStudNameTbox.Text = (reader["studname"].ToString());
                            this.updateCourseTbox.Text = (reader["course"].ToString());
                            this.updateSectionTbox.Text = (reader["section"].ToString());
                            this.updateYearTbox.Text = (reader["year_level"].ToString());
                            this.updateCollegeTbox.Text = (reader["department"].ToString());
                        }
                    }
                    else
                    {
                        MessageBox.Show("NO MATCHING RECORDS");
                    }
                }
                catch (Exception)
                {
                    MessageBox.Show("COULD NOT CONNECT TO DATABASE\nPLEASE CONTACT ADMINISTRATOR");
                }
                connection.Close();
        }

        private void updateButton_Click(object sender, EventArgs e)
        {
            string search_id = this.searchStudButton.Text;
            string stud_id = this.updateStudIdTbox.Text;
            string studname = this.updateStudNameTbox.Text;
            string course = this.updateCourseTbox.Text;
            int year = System.Convert.ToInt32(this.updateYearTbox.Text);
            string section = this.updateSectionTbox.Text;
            string department = this.updateCollegeTbox.Text;

            MySqlConnectionStringBuilder connBuilder = new MySqlConnectionStringBuilder();

            connBuilder.Add("Database", "grade_inquiry");
            connBuilder.Add("Data Source", "localhost");
            connBuilder.Add("User Id", "root");
            connBuilder.Add("Password", "");

            MySqlConnection connection = new MySqlConnection(connBuilder.ConnectionString);
            connection.Open();

            try
            {
                MySqlCommand update = new MySqlCommand("UPDATE students SET student_school_id='" + stud_id + "' WHERE student_school_id ='" + search_id + "'", connection);
                MySqlDataReader reader = update.ExecuteReader();
                MessageBox.Show("SUCCESS");
            }
            catch (Exception)
            {
                MessageBox.Show("ERROR");
            }
            connection.Close();
        }
    }
}

我不知道我单击更新按钮后，但我检查了数据库，但未进行任何更改，这表示成功了。我只是尝试仅使用student_school_id列进行更新，这不是我表中的主键，而是一个唯一列，以防止重复。