Simple Insert ,Delete,Update,Edit ,Duplicate value option with Data Grid View

This is UI part of  practice application .
===========================================
and code are given below for this:(Form1.CS page)





using System;
using System.Windows.Forms;
using ConnectToDataBase;//this is from Library file.

namespace GroupMailingSystem
{
    public partial class Form1 : Form
    {
        Class1 tempClass = new Class1();
        public static string tempGroup = string.Empty;
        public Form1()
        {
            InitializeComponent();
        }
        //code for insert button.
        private void button1_Click(object sender, EventArgs e)
        {
            string groupName = txtAddGroup.Text.Trim();
            var set = tempClass.FromDatabase("SELECT COUNT(*) FROM [dbo].[Tab_GroupName] WHERE Groupname='" + txtAddGroup.Text + "' and IsDeleted=0");
            if (!(Convert.ToInt32(set.Tables[0].Rows[0][0].ToString()) > 0))
            {
                tempClass.InsertDataIntoDatabase("INSERT [dbo].[Tab_GroupName] ( [GroupName],[IsDeleted]) VALUES ('" + groupName + "',0)");
                lblError.Text = "successfully inserted";
            }
            else
                lblError.Text = "Already data with same name.";
            ShowDataInGridview();
         
        }

        private void ShowDataInGridview()
        {
            dataGridView1.DataSource = tempClass.FromDatabase("SELECT GroupName FROM [dbo].[Tab_GroupName] WHERE IsDeleted=0");
            dataGridView1.DataMember = "Tables";
        }
        //code for next button click.
        private void button2_Click(object sender, EventArgs e)
        {
            Form2 frm = new Form2(this);
            frm.Show();
            this.Hide();

        }

        //on form loading.
        private void Form1_Load(object sender, EventArgs e)
        {
            ShowDataInGridview();
            int rowToBeSelected = 0;//3; // third row
            if (dataGridView1.Rows.Count >= rowToBeSelected)
            {
                // Since index is zero based, you have to subtract 1
                dataGridView1.Rows[rowToBeSelected - 1].Selected = true;
            }
        }
        //code for Edit button click.
        private void button3_Click(object sender, EventArgs e)
        {
            int i;
            i = dataGridView1.SelectedCells[0].RowIndex;
            txtAddGroup.Text = dataGridView1.Rows[i].Cells[0].Value.ToString();
            tempGroup = txtAddGroup.Text;
        }
        //code for  UPdate button.
        private void button5_Click(object sender, EventArgs e)
        {

            var set = tempClass.FromDatabase("SELECT COUNT(*) FROM [dbo].[Tab_GroupName] WHERE Groupname='" + txtAddGroup.Text + "'  and IsDeleted=0");
            if (!(Convert.ToInt32(set.Tables[0].Rows[0][0].ToString()) > 0))
            {
                int success = tempClass.UpdateGroupIntoDatabase("UPDATE  [dbo].[Tab_GroupName] SET GroupName=@Name WHERE (GroupName='" + tempGroup + "')", txtAddGroup.Text);
                if (success > 0)
                {
                    txtAddGroup.Text = string.Empty;
                    lblError.Text = "successfully updated.";
                }
                else
                    lblError.Text = "unsuccessful .";
                ShowDataInGridview();

            }
        }


         //code for  delete button.
        private void button4_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("Do you want to delete?", "Delete data", MessageBoxButtons.YesNo) == DialogResult.Yes)
            {
                // a 'DialogResult.Yes' value was returned from the MessageBox
                // proceed with your deletion

                #region This code is used for deleting rows from database where Id is not Identity spceify.
                //int i;
                //i = dataGridView1.SelectedCells[0].RowIndex;
                //if (dataGridView1.Rows.Count > 1 && i != dataGridView1.Rows.Count - 1)
                //{
                //    tempClass.DeleteRowFromDatabase("DELETE FROM [dbo].[Tab_GroupName] WHERE ID=" + dataGridView1.SelectedCells[0].RowIndex + "");
                //    dataGridView1.Rows.RemoveAt(dataGridView1.SelectedRows[i].Index);
                //}
                //ShowDataInGridview();
                #endregion
                int temp = dataGridView1.SelectedCells[0].RowIndex;
                #region When Id is Identity specify and you dont want data from database
                int success = tempClass.DeleteRowFromDatabase("UPDATE  [dbo].[Tab_GroupName] SET IsDeleted=1 WHERE ID=" + (temp + 1) + "");
                if (success > 0)
                {
                    txtAddGroup.Text = string.Empty;
                    lblError.Text = "successfully updated.";
                }
                else
                    lblError.Text = "unsuccessful .";
                ShowDataInGridview();
                #endregion

            }
        }
    }
}

==========================================================

for ConnectToDataBase (add a library project and reference it)

using System;

using System.Data;

using System.Data.SqlClient;

using ConnectToDataBase;

namespace ConnectToDataBase

{

    public class Class1

    {

        private static int temp = 0;

        SqlConnection con = new SqlConnection("Data Source=YourServerName;Initial Catalog=DataBaseName;Integrated Security=True");

        DataSet ds = null;

        public DataSet FromDatabase(string query)

        {

            con.Open();

            SqlDataAdapter da = new SqlDataAdapter(query, con);

            ds = new DataSet();

            da.Fill(ds, "Tables");

            con.Close();

            return ds;

        }

        public int InsertDataIntoDatabase(string query)

        {

            try

            {

                con.Open();

                SqlCommand cmd = new SqlCommand(query, con);

                if (cmd.ExecuteNonQuery() > 0)

                {

                    temp = 1;

                }

            }

            catch (Exception ex)

            {

                temp = 3;

            }

            finally

            {

                con.Close();

            }

            return temp;

        }

        public int DeleteRowFromDatabase(string query)

        {

            con.Open();

            SqlCommand delcmd = new SqlCommand(query, con);

            if (delcmd.ExecuteNonQuery() > 0)

            {

                con.Close();

                return 1;

            }

            con.Close();

            return 0;

        }

        public int UpdateGroupIntoDatabase(string query, string newGroup)

        {

            con.Open();

            SqlCommand cmd = new SqlCommand(query, con);

            cmd.Parameters.AddWithValue("@Name", newGroup);

            if (cmd.ExecuteNonQuery() > 0)

            {

                con.Close();

                return 1;

            }

            con.Close();

            return 0;

        }

    }

}

=================================

and Script file for database:

USE [DataBaseName]

CREATE TABLE [dbo].[Tab_GroupName](

[Id] [int] IDENTITY(1,1) PRIMARY KEY, 

[GroupName] [varchar](50) NOT NULL,

[IsDeleted] [bit] NOT NULL)

GO

CREATE TABLE [dbo].[Tab_User](

[Id] [int] IDENTITY(1,1) NOT NULL, 

[Name] [varchar](50) NOT NULL,

[Email] [varchar](50) NOT NULL,

[PhoneNumber] [bigint] NOT NULL,

[GroupId] [int] NOT NULL,

[IsDeleted] [bit] NOT NULL,

PRIMARY KEY([GroupId],[PhoneNumber]))

GO

ALTER TABLE [dbo].[Tab_User]  WITH CHECK ADD  CONSTRAINT [FK_Tab_User_Tab_GroupName] FOREIGN KEY([GroupId])

REFERENCES [dbo].[Tab_GroupName] ([Id])

GO

ALTER TABLE [dbo].[Tab_User] CHECK CONSTRAINT [FK_Tab_User_Tab_GroupName]

GO