Sqltransaction

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 SqlTransactionClassinAdodotNet
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        SqlConnection conn;
        SqlCommand comm1, comm2, comm3;
        SqlTransaction trans;
        SqlDataAdapter adapter1, adapter2;
        DataSet ds1, ds2;
        string constring = @"Data Source=BHARTIJILEDAR\SQLEXPRESS;Initial Catalog=test;User ID=sa;Password=1234";
        private void Form1_Load(object sender, EventArgs e)
        {
            conn = new SqlConnection(constring);
            conn.Open();
            comm1 = new SqlCommand("select userid from userdet", conn);
            SqlDataReader reader = comm1.ExecuteReader();
            while (reader.Read())
            {
                cmbuserid.Items.Add(reader[0]);
            }
            reader.Close();
            conn.Close();
        }

        private void btnshowrecord_Click(object sender, EventArgs e)
        {
            adapter1 = new SqlDataAdapter("select * from userdet", constring);
            adapter2 = new SqlDataAdapter("select * from moneytrans1", constring);
            ds1 = new System.Data.DataSet();
            adapter1.Fill(ds1);
            ds2 = new System.Data.DataSet();
            adapter2.Fill(ds2);
            dgvforuserdet.DataSource = ds1.Tables[0];
            dgvformoneytrans1.DataSource = ds2.Tables[0];
        }

        private void btnok_Click(object sender, EventArgs e)
        {
         
            if (txtamount.Text == "" || cmbuserid.Text == "")
            {
                MessageBox.Show("Plz, Write Amout");
            }
            else
            {
            conn = new SqlConnection(constring);
            conn.Open();
            comm2 = new SqlCommand("insert into moneytrans1 values(" + cmbuserid.SelectedItem.ToString() + "," + txtamount.Text + ")", conn);
            comm3 = new SqlCommand("update userdet set amount=amount-'" + txtamount.Text + "' where userid="+ cmbuserid.SelectedItem.ToString()+" ", conn);
            trans = conn.BeginTransaction();
            comm2.Transaction = trans;
            comm3.Transaction = trans;
                try
                {
                comm2.ExecuteNonQuery();
                comm3.ExecuteNonQuery();
                trans.Commit();
                        MessageBox.Show("Transaction Complted. ");
                    }
                    catch (Exception)
                    {
                        trans.Rollback();
                        MessageBox.Show("Transaction Failed..");
                    }
                }
                conn.Close();
            }
        }
    }

Sign In with valid user with execute scaler

private int IsValidUser()
{            
    int result = 0;
    string strQuery = "Select Email From AUser Where Email = @Email And Password = @Password ";
    SqlConnection con = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["ConnectionString"]);

    SqlCommand Cmd = new SqlCommand(strQuery, con);
    //Cmd.CommandType = CommandType.StoredProcedure;

    Cmd.Parameters.AddWithValue("@Email", txtEmail.Text);
    Cmd.Parameters.AddWithValue("@Password", txtPassword.Text);
    con.Open();

    result = (int)Cmd.ExecuteScalar();

    if (result > 0)
    {
        //Session["SessionEmail"] = txtEmail.Text;
        Session[General.S_USEREMAIL] = txtEmail.Text;
        Response.Redirect("~/frmMyAccountMyProfile.aspx");
    }
    else
    {
        Literal1.Text = "Invalid Email/Password!";
    }
}

datatable concept

  DataTable dt = new DataTable();


        private void button1_Click(object sender, EventArgs e)
        {
            dt.Columns.Add("SSN", typeof(string));
            dt.Columns.Add("NAME", typeof(string));
            dt.Columns.Add("ADDR", typeof(string));
            dt.Columns.Add("AGE", typeof(int));
            DataColumn[] KEY = new DataColumn[1];
            KEY[0] = dt.Columns[0];
            dt.PrimaryKey = KEY;
            dt.Rows.Add("203456843", "BHARTIJILEDAR", "13 Main Ct, Newyork, NY", 27);
            dt.Rows.Add("203456877", "SAM", "13 Main Ct, Newyork, NY", 25);
            dt.Rows.Add("203456878", "Elan", "14 Main Street, Newyork, NY", 35);
            dt.Rows.Add("203456879", "Smith", "12 Main Street, Newyork, NY", 45);
            dt.Rows.Add("203456880", "SAM", "345 Main Ave, Dayton, OH", 55);
            dt.Rows.Add("203456881", "Sue", "32 Cranbrook Rd, Newyork, NY", 65);
            dt.Rows.Add("203456882", "Winston", "1208 Alex St, Newyork, NY", 65);
            dt.Rows.Add("203456883", "Mac", "126 Province Ave, Baltimore, NY", 85);
            dt.Rows.Add("203456884", "SAM", "126 Province Ave, Baltimore, NY", 95);
            //RETREAVING THE DATA HAVING NAME NOT BE SAME
            foreach (DataRow o in dt.Select("NAME <> 'SAM'"))
            {
                //MessageBox.Show("\t" + DR["SSN"] + "\t" + DR["NAME"] + "\t" + DR["ADDR"] + "\t" + DR["AGE"]);
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + "\t" + o["NAME"] + "\t" + "\t" + o["ADDR"] + "\t" + o["AGE"]);

            }
            listBox1.Items.Add(" CHECKING THE AGE GREATER THEN 60");
            foreach (DataRow o in dt.Select("AGE>60").Take(2))
            {
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + "\t" + o["NAME"] + "\t" + "\t" + o["ADDR"] + "\t" + o["AGE"]);

            }
         
            listBox1.Items.Add(" AGE IN DECENDING ORDER");

            foreach (DataRow o in dt.Select( " ", "AGE DESC"))
            {
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + "\t" + o["NAME"] + "\t" + "\t" + o["ADDR"] + "\t" + o["AGE"]);

            }
            listBox1.Items.Add("name ascending order");
            foreach (DataRow o in dt.Select(" ", "NAME ASC"))
            { listBox1.Items.Add("\t" + o["SSN"] + "\t" + "\t" + o["NAME"] + "\t" + "\t" + o["ADDR"] + "\t" + o["AGE"]);

            }
            // Console.WriteLine(" The average of all the person's age is: " + avgAge);
            listBox1.Items.Add(" getting the name of most age person in the list");
            DataRow MOSTAGEDPERSON = dt.Select("", "AGE ASC").Last();
            {
                listBox1.Items.Add("\t" + MOSTAGEDPERSON["SSN"] + "\t" + "\t" + MOSTAGEDPERSON["NAME"] + "\t" + "\t" + MOSTAGEDPERSON["ADDR"] + "\t" + MOSTAGEDPERSON["AGE"]);


            }
           
            listBox1.Items.Add(" PERSON HAVING AGE GREATER THEN 60");
            foreach (DataRow o in dt.Select().SkipWhile(m => (int)m.ItemArray[3] < 60))
            {
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + "\t" + o["NAME"] + "\t" + "\t" + o["ADDR"] + "\t" + o["AGE"]);

            }

         
           listBox1.Items.Add(" Displaying the persons until we find a person with name starts with other than 'S'");
            foreach (DataRow o in dt.Select().Where(m => m.ItemArray[1].ToString().StartsWith("S")))
            {
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + o["NAME"] + "\t" + o["ADDR"] + "\t" + o["AGE"]);
            }

         
            listBox1.Items.Add("\n Checking all the persons have SSN or not ...");
            if (dt.Select().All(m => m.ItemArray[0] != null))
            {
                listBox1.Items.Add("\t No person is found without SSN");
            }

            Console.WriteLine("\n-----------------------------------------------------------------------------");
            listBox1.Items.Add("\n Finding the person whose SSN = 203456876 in the list");
            foreach (DataRow o in dt.Select("SSN = '203456876'"))
            {
                listBox1.Items.Add("\t" + o["SSN"] + "\t" + o["NAME"] + "\t" + o["ADDR"] + "\t" + o["AGE"]);
            }
            Console.WriteLine("\n-----------------------------------------------------------------------------");
            Console.Read();
            listBox1.Items.Add("HECKING  THE AGE BETWEEN 13  AND 19  WCHICH IS CALLED TEEN AGE");
            if (dt.Select("AGE >= 13 AND AGE <= 19").Any())
            {
                MessageBox.Show("yeS WE HAVE TEEN AGERS IN LIST");
            }
            else
            {
                MessageBox.Show("NO, WE nO  HAVE TEEN AGERS IN LIST");

            }
            Console.WriteLine("\n-----------------------------------------------------------------------------");
            Console.WriteLine("\n Checking whether a person having name 'SAM' exists or not...");
            if (dt.Select().Any(m => m.ItemArray[1].ToString() == "SAM"))
            {
                MessageBox.Show("Person having the NAme  Sam");
            }
            Console.WriteLine("\n Getting Average of all the person's age...");
            double Sumage = dt.Select("").Average(m => (int)m.ItemArray[3]);
            // double avgAge = dt.Select("").Average(m => (int)m.ItemArray[3]);
            MessageBox.Show("The Sum Of All Person Age Is" + Sumage);
         
        }


        private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
        {

        }
    }
}

Use Sql Parameter in C#

    public string GetConnectionString()
    {
        //we will set up the configuration which will call our
        //web.config file to provide the database details because
        //in configuration file we have created the <connectionStrings>
        //in the process we draged and droped. It creates automatically.
        //We normally put the database details in web.config file or
        //machine.config file because it is very sensitive information
        //usually there IP address of remote database, passwords and
        //user names are stored.

        return System.Configuration.ConfigurationManager.ConnectionStrings
            ["onlineapplicationformConnectionString1"].ConnectionString;
        //in above line "onlineapplicationformConnectionString1" is
        //our configuration name which is inside the web.config file.
    }

    private void execution(string fname, string lname, string dob, string gender, string fathername, string contact, string address)
    {      
        //In above line we declaring different variables same as backend
        SqlConnection conn = new SqlConnection(GetConnectionString());
        //In above line we are calling connection
        //string function which is defined already on top
        string sql = "INSERT INTO regiistrationform (fname, lname, dob, gender, fathername, contact, per_address) VALUES "
        + " (@fname, @lname, @dob, @gender, @fathername, @contact, @per_address)";
        //In above lines we are just storing the sql commands which
        //will insert value in onlineapplication named table,
        //using variable named sql.
        try
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand(sql, conn);
            //In above lines we are opening the connection to work and
            //also storing connection name and sql command in cmd variable
            //which has 'SqlCommand' type.
            SqlParameter[] pram = new SqlParameter[7];
 
            //In above lines we are defining 7 sql parameters will be use
            //In below lines we will not disscuss about id column
            pram[0] = new SqlParameter("@fname", SqlDbType.VarChar, 10);
            pram[1] = new SqlParameter("@lname", SqlDbType.VarChar, 50);
            pram[2] = new SqlParameter("@dob", SqlDbType.VarChar, 50);
            pram[3] = new SqlParameter("@gender", SqlDbType.Char, 10);
            pram[4] = new SqlParameter("@fathername", SqlDbType.VarChar, 50);
            pram[5] = new SqlParameter("@contact", SqlDbType.Int, 20);
            pram[6] = new SqlParameter("@per_address", SqlDbType.VarChar, 100);
            //Now we set-uped all fiels in database in above lines
            //Now we will set-up form fields
            pram[0].Value = fname;
            pram[1].Value = lname;
            pram[2].Value = Convert.ToDateTime ( dob);
            pram[3].Value = gender;
            pram[4].Value = fathername;
            pram[5].Value = Convert.ToInt32( contact);
            pram[6].Value = address;
            //Now create loop to insert
            for (int i = 0; i < pram.Length; i++)
            {
                cmd.Parameters.Add(pram[i]);
            }
            for (int i = 0; i < pram.Length; i++)
            {
                cmd.Parameters.Add(pram[i]);
            }
            cmd.CommandType = CommandType.Text;
            cmd.ExecuteNonQuery();
        }
        catch(System.Data.SqlClient.SqlException ex_msg)
        {
            //Here will be catch elements
            string msg = "Error occured while inserting";
            msg += ex_msg.Message;
            throw new Exception(msg);
        }
        finally
        {
            //Here will be fially elements
            conn.Close();
        }
   
    }

    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void submit_Click(object sender, EventArgs e)
    {
        //Here is the command inside the click event of button
        if(fname.Text=="")
        {
            Response.Write("Please complete the form.");
        }
        else
        {
            execution(fname.Text,lname.Text,dob.Text,gender.Text,fathername.Text,contact.Text,address.Text);
            conform.Visible = true;
            fname.Text="";
            lname.Text="";
            dob.Text="";
            gender.Text="";
            gender.Text="";
            fathername.Text="";
            contact.Text="";
            address.Text="";
        }
    }
    protected void gender_TextChanged(object sender, EventArgs e)
    {
}
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection conn = new SqlConnection(GetConnectionString());
        //In above line we are calling connection
        //string function which is defined already on top
        conn.Open();


        string sql = "select * from regiistrationform";
        SqlCommand cmd = new SqlCommand(sql, conn);
        SqlDataAdapter adapter = new SqlDataAdapter(cmd);
        DataTable dt =new DataTable();
        adapter.Fill(dt);
       
        string strName =dt.Rows.Add("fname").ToString();
    foreach (DataRow dr in dt.Rows )
    {
     

        }

    }
}

Call By References

 class PassingRefByRef

    {

        static void Change(ref int[] pArray)

        {

            // Both of the following changes will affect the original variables:

            pArray[0] = 888;

            pArray = new int[5] { -3, -1, -2, -3, -4 };

            System.Console.WriteLine("Inside the method, the first element is: {0}", pArray[0]);

            Console.ReadLine();

        }

        static void Main()

        {

            int[] array = { 2, 3, 6, 7 };

            System.Console.WriteLine("The No Before Calling the ,The first element is{0}", array[0]);

            int[] arr = { 1, 4, 5 };

            System.Console.WriteLine("Inside Main, before calling the method, the first element is: {0}", arr[0]);

           Change(ref arr);

            System.Console.WriteLine("Inside Main, after calling the method, the first element is: {0}", arr[0]);

            Console.ReadLine();

        }

    }