Select Unique Values

Course  Branch  ExamType         Month  Year
B-TECH	CIVIL	Supplementary	October	2011												
B-TECH	CIVIL	Supplementary	October	2011									
B-TECH	ECE	Regular	        April	2011	

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

namespace StudentDetails
{
    public partial class StudentDetails : Form
    {
        //SqlConnection con = new SqlConnection("Password=123;Persist Security Info=True;User ID=sa;Initial Catalog=C M S;Data Source=NITHYANANDAM");
        SqlConnection con = new SqlConnection("Password=123;Persist Security Info=True;User ID=sa;Initial Catalog=C M S;Data Source=SHIRISHAJALLU");
        SqlDataAdapter da,da1;
        SqlDataReader dr;
        SqlCommand cmd;
        DataSet ds;
        String Cb="empty";
        string rcfu = string.Empty;
        public StudentDetails()
        {
            InitializeComponent();
        }

        private void StudentDetails_Load(object sender, EventArgs e)
        {
            combofill();
            groupfill();
            groupBox1.Visible = false;
            dgvstudentwise.Visible = false;
            dgvsmemo.Visible = false;
            btnsave.Visible = false;
         }
        private void combofill()
        {
            if (con.State == 0)
            {
                con.Open();
            }
            cmd = new SqlCommand("select Course,Branch,Year,Semister,ExamType,MonthofAppear,YearofAppear from ExamEntry group by Course,Branch,Year,Semister,ExamType,MonthofAppear,YearofAppear", con);
            dr = cmd.ExecuteReader();
            while (dr.Read())
                {
                    cmbcourse.Items.Add(dr.GetString(0));
                    cmbbranch.Items.Add(dr.GetString(1));
                    cmbyear.Items.Add(dr.GetString(2));
                    cmbsem.Items.Add(dr.GetString(3));
                    cmbexamtype.Items.Add(dr.GetString(4));
                    cmbmonthofappear.Items.Add(dr.GetString(5));
                    cmbyearofappear.Items.Add(dr.GetString(6));

                }
                    
            dr.Close();
            con.Close();


        }
               
        private void btnclose_Click(object sender, EventArgs e)
        {
            this.Close();
        }
        private void btnsubmit_Click(object sender, EventArgs e)
        {
                dgvsmemo.Visible = true;
                btnsave.Visible = true;
                btnsearchstudentwise.Visible = true;
                dgvsmemo.Columns.Clear();
                DataGridViewCheckBoxColumn cl = new DataGridViewCheckBoxColumn();
                cl.Name = "CertificatesReceivedFromUniversity" ;
                cl.HeaderText = "CertificatesReceivedFromUniversity";
                cl.Width = 80;                      
                dgvsmemo.Columns.Add(cl);
                dgvsmemo.Columns[0].DefaultCellStyle.BackColor = Color.White;
                con.Open();
                da = new SqlDataAdapter("Select StudentID,SName as StudentName,Course,Branch,Year,Semister,ExamType,MonthofAppear,YearofAppear from ExamEntry where Course='" + cmbcourse.Text + "' and Branch='" + cmbbranch.Text + "' and Year='" + cmbyear.Text + "' and  Semister='" + cmbsem.Text + "' and ExamType='" + cmbexamtype.Text + "' and MonthofAppear='" + cmbmonthofappear.Text + "' and YearofAppear='" + cmbyearofappear.Text + "'", con);
                ds = new DataSet();
                ds.Tables.Clear();
                da.Fill(ds, "ExamEntry");             
                dgvsmemo.DataSource = ds.Tables["ExamEntry"];
               
          

            con.Close();
        }
        private void cmbcourse_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (cmbcourse.Text == "MCA")
            {

            }
        }
        private void clear()
        {
            cmbcourse.Text = "";
            cmbbranch.Text = "";
            cmbyear.Text = "";
            cmbsem.Text = "";
            cmbexamtype.Text = "";
            cmbmonthofappear.Text = "";
            cmbyearofappear.Text = "";
            
        }
        private void btnsave_Click(object sender, EventArgs e)
        {

            string StudentID = string.Empty, Sname = string.Empty, Course = string.Empty, Branch = string.Empty, Year = string.Empty, Semister = string.Empty, ExamType = string.Empty, MonthofAppear = string.Empty, YearofAppear = string.Empty;
            int i = dgvsmemo.RowCount;
            for (int j = 0; j < i; j++)
            {
                DataGridViewCheckBoxCell c1 = new DataGridViewCheckBoxCell();
                c1 = (DataGridViewCheckBoxCell)dgvsmemo.Rows[j].Cells[0];
                if (c1.Value == null)
                    c1.Value = false;
                switch (c1.Value.ToString())
                {
                    case "True":
                        Cb = "Yes";
                        break;
                    case "False":
                        Cb = "No";
                        break;
                }
                
                StudentID = dgvsmemo.Rows[j].Cells["StudentID"].Value.ToString();
                Sname = dgvsmemo.Rows[j].Cells["StudentName"].Value.ToString();
                Course = dgvsmemo.Rows[j].Cells["Course"].Value.ToString();
                Branch = dgvsmemo.Rows[j].Cells["Branch"].Value.ToString();
                Year = dgvsmemo.Rows[j].Cells["Year"].Value.ToString();
                Semister = dgvsmemo.Rows[j].Cells["Semister"].Value.ToString();
                ExamType = dgvsmemo.Rows[j].Cells["ExamType"].Value.ToString();
                MonthofAppear = dgvsmemo.Rows[j].Cells["MonthofAppear"].Value.ToString();
                YearofAppear = dgvsmemo.Rows[j].Cells["YearofAppear"].Value.ToString();
                con.Open();
                cmd = new SqlCommand("insert into StudentMemoDetails values('" + Cb + "','" + StudentID + "','" + Sname + "','" + Course + "','" + Branch + "','" + Year + "','" + Semister + "','" + ExamType + "','" + MonthofAppear + "','" + YearofAppear + "')", con);
                cmd.ExecuteNonQuery();
                con.Close();
                MessageBox.Show("Certificates Details Saved Successfully");
                clear();
            }

        }

        private void btncancel_Click(object sender, EventArgs e)
        {
            cmbstudentid.Text = "";
            dgvstudentwise.Visible = false;
            groupBox1.Visible = false;
        }

        private void groupfill()
        {
            if (con.State == 0)
            {
                con.Open();
            }
            cmd = new SqlCommand("select distinct StudentID from ExamEntry", con);
            dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                cmbstudentid.Items.Add(dr.GetString(0));
            }

            dr.Close();
            con.Close();
        }

        private void btnok_Click(object sender, EventArgs e)
        {
            dgvstudentwise.Visible = true;
            da1 = new SqlDataAdapter("Select * from StudentMemoDetails where StudentID='"+cmbstudentid.Text+"'",con);
            ds = new DataSet();
            ds.Tables.Clear();
            da1.Fill(ds, "StudentMemoDetails");
            dgvstudentwise.DataSource = ds.Tables["StudentMemoDetails"];
               
        }

       
        private void btnsearchstudentwise_Click(object sender, EventArgs e)
        {
            groupBox1.Visible = true;
        }
                 
                                                   
    }
}