csharp DB CRUD（C＃Windows窗体）.cs

Posted 2021-05-12

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

namespace Database_CRUD_CS__with_SQL_Server_
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnInsert_Click(object sender, EventArgs e)
        {
            Student student = new Student();
            student.Name = txtName.Text;
            student.Reg = txtReg.Text;
            student.Address = txtAddress.Text;


            //CONNECT TO DATABASE
            string connectionString = @"Server=(local); " +"Database=UniversityManagementDB; " + "Integrated Security=TRUE;";
            SqlConnection connection = new SqlConnection(connectionString);



            //WRITE INSERT QUERY
            string query = "INSERT INTO tbl_student VALUES('"+student.Name+"','" + student.Reg+"','" + student.Address + "')";



            // EXECUTE THE QUERY
            SqlCommand command = new SqlCommand(query, connection);
            // Two OTHER ways 
            /* SqlCommand command = new SqlCommand { Connection = connection, CommandText = query}; */
            /* SqlCommand command = new SqlCommand{}; */
            /* command.CommandText = query;
               command.Connection = connection; */

            connection.Open();
            int rowAffected = command.ExecuteNonQuery();
            connection.Close();
            if (rowAffected > 0) MessageBox.Show("Inserted "+rowAffected+" Records Successfully");
            else MessageBox.Show("Error! Sorry No row inserted");            
        }

        private void btnSelect_Click(object sender, EventArgs e)
        {
            getAllStudents();
        }

        public void getAllStudents()
        {
            // CONNECT TO DATABASE
            string connectionSring = "Server=(local); Database=UniversityManagementDB; Integrated Security=TRUE;";
            SqlConnection connection = new SqlConnection(connectionSring);


            // WRITE THE QUERY
            string query = "SELECT * FROM tbl_student";


            // EXECUTE THE QUERY 
            /* read data from database and populate list of objects */
            SqlCommand command = new SqlCommand(query, connection);
            connection.Open();

            SqlDataReader reader = command.ExecuteReader();
            List<Student> studentList = new List<Student>();
            while (reader.Read())
            {
                Student student = new Student();
                student.ID = int.Parse(reader["ID"].ToString());
                student.Name = reader["Name"].ToString();
                student.Reg = reader["Reg"].ToString();
                student.Address = reader["Address"].ToString();
                studentList.Add(student);
            }
            reader.Close();
            connection.Close();


            /* populate listview with student list */
            listviewStudents.Items.Clear();
            foreach (Student student in studentList)
            {
                ListViewItem item = new ListViewItem();
                item.Text = student.ID.ToString();
                item.SubItems.Add(student.Name);
                item.SubItems.Add(student.Reg);
                item.SubItems.Add(student.Address);
                item.Tag = student; 
                listviewStudents.Items.Add(item);
            }
        }

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            Student student = new Student();
            student.ID = int.Parse(lblID.Text);
            student.Name = txtName.Text;
            student.Reg = txtReg.Text;
            student.Address = txtAddress.Text;


            //CONNECT TO DATABASE
            string connectionString = @"Server=(local); " + "Database=UniversityManagementDB; " + "Integrated Security=TRUE;";
            SqlConnection connection = new SqlConnection(connectionString);



            //WRITE UPDATE QUERY
            string query = "UPDATE  tbl_student SET Name='" + student.Name + "', Reg='" + student.Reg + "', Address='" + student.Address + "' WHERE ID='"+student.ID+"';";


            // EXECUTE THE QUERY
            SqlCommand command = new SqlCommand(query, connection);


            connection.Open();
            int rowAffected = command.ExecuteNonQuery();
            connection.Close();

            if (rowAffected > 0)
            {
                getAllStudents();
                resetFields();
                MessageBox.Show("Row Updated Successfully");
            }
            else MessageBox.Show("Error! Sorry No row updated");
        }

        public void resetFields()
        {
            lblID.Text = string.Empty;
            txtName.Text = string.Empty;
            txtReg.Text = string.Empty;
            txtAddress.Text = string.Empty;
        }

        private void listviewStudents_DoubleClick(object sender, EventArgs e)
        {
            if (listviewStudents.SelectedItems.Count > 0)
            {
                ListViewItem selectedItem = listviewStudents.SelectedItems[0];
                Student selectedStudent = (Student) selectedItem.Tag;
                txtName.Text = selectedStudent.Name;
                txtReg.Text = selectedStudent.Reg;
                txtAddress.Text = selectedStudent.Address;
                lblID.Text = selectedStudent.ID.ToString();
            }
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            int id = int.Parse(lblID.Text);

            //CONNECT TO DATABASE
            string connectionString = @"Server=(local); " + "Database=UniversityManagementDB; " + "Integrated Security=TRUE;";
            SqlConnection connection = new SqlConnection(connectionString);



            //WRITE DELETE QUERY
            string query = "DELETE FROM tbl_student WHERE ID='"+id+"';";


            // EXECUTE THE QUERY
            SqlCommand command = new SqlCommand(query, connection);

            connection.Open();
            int rowAffected = command.ExecuteNonQuery();
            connection.Close();
            if (rowAffected > 0)
            {
                getAllStudents();
                resetFields();
                MessageBox.Show("Deleted " + rowAffected + " Records Successfully");
            }
            else MessageBox.Show("Error! Sorry No row deleted");
        }
    }

    public class Student
    {
        public int ID { get; set; }
        public string Name { get; set; }
        public string Reg { get; set; }
        public string Address { get; set; }
    }
}

using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Diagnostics;

namespace VelocityFinCrime.Web.Hubs
{
    public class Test
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }
    public class NotificationService
    {
        readonly string _connString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;

        public long GetAllNotification()
        {
            var count = 0;
            using (var connection = new SqlConnection(_connString))
            {

                connection.Open();
                using (var command = new SqlCommand(@"SELECT Id,ActionType,PreviousData,NewData,ActionTable,ModifyBy,ActionBy,UserBranchId,MachineDetails,ActionDateTime FROM dbo.AuditTrails", connection))
                {
                    command.Notification = null;

                    var dependency = new SqlDependency(command);
                    dependency.OnChange += dependency_OnChange;

                    if (connection.State == ConnectionState.Closed)
                        connection.Open();

                    var reader = command.ExecuteReader();

                    while (reader.Read())
                    {
                        count++;
                    }
                }
            }
            return count;

        }
        private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
        {
            if (e.Type == SqlNotificationType.Change)
            {
                NotificationHub.Notify();
            }
            else
            {
                Debug.WriteLine(e.Type);
            }
        }
    }
}