TR_AdminPanel.cs

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

namespace EducationManagementSystem
{
    public partial class TR_AdminPanel : UserControl
    {
        SqlConnection con = new SqlConnection(@"Data Source=DESKTOP-OUS5TJV\SQLEXPRESS;database=OOPProject;UID=helloworld;password=hello");
        public TR_AdminPanel()
        {
            InitializeComponent();
        }

        private void pictureBox2_Click(object sender, EventArgs e)
        {
            TRegister TR = new TRegister();
            TR.Show();
        }

        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {

        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            dataGridView1.DataSource = null;
            dataGridView1.Rows.Clear();
            SqlCommand cmd = new SqlCommand();
            con.Open();
            if (comboBox1.Text == "")
            {
                cmd = new SqlCommand("SELECT t.Id,t.Name,t.Father_Name,t.Phone,t.Age,t.Gender,t.Cnic,t.Address,t.Qualification,c.course_name from Teacher t join Course c on t.c_id=c.c_id", con);
            }
            else if (comboBox1.Text == "Id")
            {
                string searchValue = textBox1.Text;
                cmd = new SqlCommand("SELECT t.Id,t.Name,t.Father_Name,t.Phone,t.Age,t.Gender,t.Cnic,t.Address,t.Qualification,c.course_name from Teacher t join Course c on t.c_id=c.c_id where [Id] = '" + searchValue + "'", con);
            }
            else if (comboBox1.Text == "Gender")
            {
                string searchValue = textBox1.Text;
                cmd = new SqlCommand("SELECT t.Id,t.Name,t.Father_Name,t.Phone,t.Age,t.Gender,t.Cnic,t.Address,t.Qualification,c.course_name from Teacher t join Course c on t.c_id=c.c_id where [Gender] = '" + searchValue + "'", con);
            }
            else if (comboBox1.Text == "Course")
            {
                string searchValue = textBox1.Text;
                cmd = new SqlCommand("SELECT t.Id,t.Name,t.Father_Name,t.Phone,t.Age,t.Gender,t.Cnic,t.Address,t.Qualification,c.course_name from Teacher t join Course c on t.c_id=c.c_id where [Course] = '" + searchValue + "'", con);
            }
          
            SqlDataReader reader = cmd.ExecuteReader();
            DataTable dt = new DataTable();
            dt.Load(reader);
            foreach (DataRow dr in dt.Rows)
            {
                dataGridView1.Rows.Add(dr.ItemArray);
            }
            con.Close();
        }

        private void TR_AdminPanel_Load(object sender, EventArgs e)
        {

        }

        private void pictureBox3_Click(object sender, EventArgs e)
        {
            for (int rows = 0; rows < dataGridView1.Rows.Count - 1; rows++)
            {


                int valueid = (int)dataGridView1.Rows[rows].Cells[0].Value;


                string valuen = dataGridView1.Rows[rows].Cells[1].Value.ToString();
                string valuef = dataGridView1.Rows[rows].Cells[2].Value.ToString();
                string valuep = dataGridView1.Rows[rows].Cells[3].Value.ToString();
                string valuea = dataGridView1.Rows[rows].Cells[4].Value.ToString();
                string valueg = dataGridView1.Rows[rows].Cells[5].Value.ToString();
                string valuec = dataGridView1.Rows[rows].Cells[6].Value.ToString();
                string valuead = dataGridView1.Rows[rows].Cells[7].Value.ToString();
                string valueq = dataGridView1.Rows[rows].Cells[8].Value.ToString();

                SqlConnection con = new SqlConnection(@"Data Source=DESKTOP-K8AHF02\SQLEXPRESS01;database=OOPProject;UID=helloworld;password=hello");
                con.Open();
                SqlCommand cmd = new SqlCommand("Update Teacher SET Name=@n , Father_Name = @f ,Phone = @p, Age = @ag , Gender = @g , CNIC = @cn, Address = @add, Qualification = @quali  Where Id = @id", con);
                cmd.Parameters.AddWithValue("@n", valuen);
                cmd.Parameters.AddWithValue("@f", valuef);
                cmd.Parameters.AddWithValue("@p", valuep);
                cmd.Parameters.AddWithValue("@ag", valuea);
                cmd.Parameters.AddWithValue("@g", valueg);
                cmd.Parameters.AddWithValue("@cn", valuec);
                cmd.Parameters.AddWithValue("@add", valuead);
                cmd.Parameters.AddWithValue("@quali", valueq);
                cmd.Parameters.AddWithValue("@id", valueid);


                cmd.ExecuteNonQuery();

                con.Close();


            }

            }
    }
}